RESUMO
Oncogene E6 plays a critical role in the development and progression of esophageal cancer caused by human papillomavirus (HPV) infection. Alpha-ketoglutarate (AKG) is a key metabolite in the tricarboxylic acid cycle and has been widely used as a dietary and anti-ageing supplement. In this study, we found that treating esophageal squamous carcinoma cells with a high dose of AKG can induce cell pyroptosis. Furthermore, our research confirms that HPV18 E6 inhibits AKG-induced pyroptosis of esophageal squamous carcinoma cells by lowering P53 expression. P53 downregulates malate dehydrogenase 1 (MDH1) expression; however, MDH1 downregulates L-2-hydroxyglutarate (L-2HG) expression, which inhibits a rise in reactive oxygen species (ROS) levels-as L-2HG is responsible for excessive ROS. This study reveals the actuating mechanism behind cell pyroptosis of esophageal squamous carcinoma cells induced by high concentrations of AKG, and we posit the molecular pathway via which the HPV E6 oncoprotein inhibits cell pyroptosis.
Assuntos
Neoplasias Esofágicas , Carcinoma de Células Escamosas do Esôfago , Proteínas Oncogênicas Virais , Infecções por Papillomavirus , Humanos , Proteína Supressora de Tumor p53/metabolismo , Neoplasias Esofágicas/metabolismo , Papillomavirus Humano 18/metabolismo , Ácidos Cetoglutáricos , Espécies Reativas de Oxigênio/metabolismo , Piroptose , Proteínas Oncogênicas Virais/metabolismo , Biomarcadores Tumorais , Proteínas Citotóxicas Formadoras de Poros/metabolismoRESUMO
Long noncoding RNAs (lncRNAs) play diverse roles in biological processes, but their expression profiles and functions in cervical carcinogenesis remain unknown. By RNA-sequencing (RNA-seq) analyses of 18 clinical specimens and selective validation by RT-qPCR analyses of 72 clinical samples, we provide evidence that, relative to normal cervical tissues, 194 lncRNAs are differentially regulated in high-risk (HR)-HPV infection along with cervical lesion progression. One such lncRNA, lnc-FANCI-2, is extensively characterized because it is expressed from a genomic locus adjacent to the FANCI gene encoding an important DNA repair factor. Both genes are up-regulated in HPV lesions and in in vitro model systems of HR-HPV18 infection. We observe a moderate reciprocal regulation of lnc-FANCI-2 and FANCI in cervical cancer CaSki cells. In these cells, lnc-FANCI-2 is transcribed from two alternative promoters, alternatively spliced, and polyadenylated at one of two alternative poly(A) sites. About 10 copies of lnc-FANCI-2 per cell are detected preferentially in the cytoplasm. Mechanistically, HR-HPVs, but not low-risk (LR)-HPV oncogenes induce lnc-FANCI-2 in primary and immortalized human keratinocytes. The induction is mediated primarily by E7, and to a lesser extent by E6, mostly independent of p53/E6AP and pRb/E2F. We show that YY1 interacts with an E7 CR3 core motif and transactivates the promoter of lnc-FANCI-2 by binding to two critical YY1-binding motifs. Moreover, HPV18 increases YY1 expression by reducing miR-29a, which targets the 3' untranslated region of YY1 mRNA. These data have provided insights into the mechanisms of how HR-HPV infections contribute to cervical carcinogenesis.
Assuntos
Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Papillomavirus Humano 16/genética , MicroRNAs/genética , Infecções por Papillomavirus/genética , RNA Longo não Codificante/genética , Neoplasias do Colo do Útero/genética , Fator de Transcrição YY1/genética , Processamento Alternativo , Sequência de Bases , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Linhagem Celular Tumoral , Colo do Útero/metabolismo , Colo do Útero/patologia , Colo do Útero/virologia , Fatores de Transcrição E2F/genética , Fatores de Transcrição E2F/metabolismo , Proteínas de Grupos de Complementação da Anemia de Fanconi/metabolismo , Feminino , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Papillomavirus Humano 16/metabolismo , Papillomavirus Humano 16/patogenicidade , Papillomavirus Humano 18/genética , Papillomavirus Humano 18/metabolismo , Papillomavirus Humano 18/patogenicidade , Humanos , Queratinócitos/metabolismo , Queratinócitos/patologia , Queratinócitos/virologia , MicroRNAs/metabolismo , Proteínas E7 de Papillomavirus/genética , Proteínas E7 de Papillomavirus/metabolismo , Infecções por Papillomavirus/metabolismo , Infecções por Papillomavirus/patologia , Infecções por Papillomavirus/virologia , Regiões Promotoras Genéticas , RNA Longo não Codificante/metabolismo , Proteína do Retinoblastoma/genética , Proteína do Retinoblastoma/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologia , Neoplasias do Colo do Útero/virologia , Fator de Transcrição YY1/metabolismoRESUMO
Human papillomavirus (HPV) is associated with cervical cancer, the third most common cancer in women. The high-risk HPV types 16 and 18 are found in over 70% of cervical cancers and produce the oncoprotein, early protein 6 (E6), which binds to p53 and mediates its ubiquitination and degradation. Targeting E6 has been shown to be a promising treatment option to eliminate HPV-positive tumor cells. In addition, combined hyperthermia with radiation is a very effective treatment strategy for cervical cancer. In this study, we examined the effect of hyperthermia on HPV-positive cells using cervical cancer cell lines infected with HPV 16 and 18, in vivo tumor models, and ex vivo-treated patient biopsies. Strikingly, we demonstrate that a clinically relevant hyperthermia temperature of 42 °C for 1 hour resulted in E6 degradation, thereby preventing the formation of the E6-p53 complex and enabling p53-dependent apoptosis and G2-phase arrest. Moreover, hyperthermia combined with p53 depletion restored both the cell-cycle distribution and apoptosis to control levels. Collectively, our findings provide new insights into the treatment of HPV-positive cervical cancer and suggest that hyperthermia therapy could improve patient outcomes.