RESUMEN
The Octamer-binding transcription factor-4 (Oct4) is upregulated in different malignancies, yet a paradigm for mechanisms of Oct4 post-embryonic re-expression is inadequately understood. In cervical cancer, Oct4 expression is higher in human papillomavirus (HPV)-related than HPV-unrelated cervical cancers and this upregulation correlates with the expression of the E7 oncogene. We have reported that E7 affects the Oct4-transcriptional output and Oct4-related phenotypes in cervical cancer, however, the underlying mechanism remains elusive. Here, we characterize the Oct4-protein interactions in cervical cancer cells via computational analyses and Mass Spectrometry and reveal that Methyl-binding proteins (MBD2 and MBD3), are determinants of Oct4-driven transcription. E7 triggers MBD2 downregulation and TET1 upregulation, thereby disrupting the methylation status of the Oct4 gene. This coincides with an increase in the total DNA hydroxymethylation leading to the re-expression of Oct4 in cervical cancer and likely affecting broader transcriptional patterns. Our findings reveal a previously unreported mechanism by which the E7 oncogene can regulate Oct4 re-expression and global transcriptional patterns by increasing DNA hydroxymethylation and lowering the barrier to cellular plasticity during carcinogenesis.
Asunto(s)
Factor 3 de Transcripción de Unión a Octámeros , Proteínas Oncogénicas Virales , Infecciones por Papillomavirus , Neoplasias del Cuello Uterino , Femenino , Humanos , ADN , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Oxigenasas de Función Mixta , Proteínas Oncogénicas Virales/genética , Proteínas E7 de Papillomavirus/genética , Proteínas Proto-Oncogénicas , Neoplasias del Cuello Uterino/genética , Neoplasias del Cuello Uterino/virología , Factor 3 de Transcripción de Unión a Octámeros/genéticaRESUMEN
Octamer binding transcription factor-4 (Oct4), is highly expressed in stem cells and has indispensable roles in pluripotency and cellular reprogramming. In contrast to other factors used for cellular reprogramming, a role for Oct4 outside embryonic stem cells has been elusive and highly controversial. Emerging evidence implicates Oct4 in the carcinogenic process, but the mechanism through which Oct4 may be functioning in cancers is not fully appreciated. Here, we provide evidence that Oct4 is expressed in human cervical cancer and this expression correlates with the presence of the human papillomavirus (HPV) oncogenes E6 and E7. Surprisingly, the viral oncogenes can complement exogenously provided Oct4 in reprogramming assays, providing functional validation for their ability to activate Oct4 transcription in Mouse Embryonic Fibroblasts (MEFs). To interrogate potential roles of Oct4 in cervical cancers we knocked-down Oct4 in HPV(+) (HeLa & CaSki) and HPV(-) (C33A) cervical cancer cell lines and found that Oct4 knockdown attenuated clonogenesis, only in the HPV(+) cells. More unexpectedly, cell proliferation and migration, were differentially affected in HPV(+) and HPV(-) cell lines. We provide evidence that Oct4 interacts with HPV E7 specifically at the CR3 region of the E7 protein and that introduction of the HPV oncogenes in C33A cells and human immortalised keratinocytes generates Oct4-associated transcriptional and phenotypic patterns, which mimic those seen in HPV(+) cells. We propose that a physical interaction of Oct4 with E7 regulates its activity in HPV(+) cervical cancers in a manner not seen in other cancer types.
Asunto(s)
Factor 3 de Transcripción de Unión a Octámeros/metabolismo , Proteínas E7 de Papillomavirus/metabolismo , Infecciones por Papillomavirus/metabolismo , Neoplasias del Cuello Uterino/metabolismo , Neoplasias del Cuello Uterino/virología , Carcinogénesis/metabolismo , Línea Celular Tumoral , Movimiento Celular/fisiología , Proliferación Celular/fisiología , Femenino , Células HeLa , Humanos , Factor 3 de Transcripción de Unión a Octámeros/biosíntesis , Factor 3 de Transcripción de Unión a Octámeros/genética , Proteínas Oncogénicas Virales/metabolismo , Oncogenes/fisiología , Papillomaviridae/genética , Papillomaviridae/metabolismo , Proteínas E7 de Papillomavirus/genética , Infecciones por Papillomavirus/patología , Infecciones por Papillomavirus/virología , Proteínas Represoras/metabolismo , Neoplasias del Cuello Uterino/genética , Neoplasias del Cuello Uterino/patologíaRESUMEN
The outcome of an inflammatory incident can hang in the balance between restoring health and tissue integrity on the one hand, and promoting aberrant tissue homeostasis and adverse outcomes on the other. Both microbial-related and sterile inflammation is a complex response characterized by a range of innate immune cell types, which produce and respond to cytokine mediators and other inflammatory signals. In turn, cells native to the tissue in question can sense these mediators and respond by migrating, proliferating and regenerating the tissue. In this review we will discuss how the specific outcomes of inflammatory incidents are affected by the direct regulation of stem cells and cellular plasticity. While less well appreciated than the effects of inflammatory signals on immune cells and other differentiated cells, the effects are crucial in understanding inflammation and appropriately managing therapeutic interventions.