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Human papillomavirus type 16 E6 and NFX1-123 mislocalize immune signaling proteins and downregulate immune gene expression in keratinocytes.

ABSTRACT: Human papillomavirus (HPV) is the most prevalent sexually transmitted infection, affecting an estimated 11% of the world's population. The high-risk HPV types (HR HPV) account for approximately 5% of the global burden of cancer and thus cause high morbidity and mortality. Although it is known that persistent infection with HR HPV is the greatest risk factor for developing HPV-associated cancer, and that the HPV early proteins E6 and E7 dysregulate immune detection by its host cells, the mechanisms of immune evasion by HR HPV are not well understood. Previous work in the laboratory identified the endogenous cytoplasmic host protein NFX1-123 as a binding partner of the HR HPV type 16 oncoprotein E6 (16E6). Together NFX1-123 and 16E6 affect cellular growth, differentiation, and immortalization genes and pathways. In a whole genome microarray, human foreskin keratinocytes (HFKs) stably expressing 16E6 and overexpressing NFX1-123 showed a diverse set of innate immune genes downregulated two-fold or more when compared to 16E6 cells with endogenous NFX1-123. We demonstrated that 16E6 and NFX1-123 decreased expression of pro-inflammatory cytokines and interferon-stimulated genes (ISGs) in 16E6 HFKs at the mRNA and protein level. Knock down of NFX1-123 in 16E6 HFKs resulted in a derepression of innate immune genes, pointing to the requirement of NFX1-123 for immune regulation in the context of 16E6. Studies using immunofluorescent microscopy revealed that 16E6 and NFX1-123 disturbed the normal localization of signaling proteins involved in initiating the immune response. This study identifies NFX1-123 as a critical host protein partner through which 16E6 is able to subvert the immune response and in turn permit a long-lived HR HPV infection.

SUBMITTER: Levan J

PROVIDER: S-EPMC5695606 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Human papillomavirus type 16 E6 and NFX1-123 mislocalize immune signaling proteins and downregulate immune gene expression in keratinocytes.

Levan Justine J Vliet-Gregg Portia A PA Robinson Kristin L KL Katzenellenbogen Rachel A RA

PloS one 20171108 11

Human papillomavirus (HPV) is the most prevalent sexually transmitted infection, affecting an estimated 11% of the world's population. The high-risk HPV types (HR HPV) account for approximately 5% of the global burden of cancer and thus cause high morbidity and mortality. Although it is known that persistent infection with HR HPV is the greatest risk factor for developing HPV-associated cancer, and that the HPV early proteins E6 and E7 dysregulate immune detection by its host cells, the mechanis ...[more]

PMID: 29117186

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Project description:PurposeHigh-risk human papillomaviruses (HR HPV) cause cervical cancer, and in these cancers, HPV type 16 is the most common HR type. The HR viral oncogenes E6 and E7 partner with cellular proteins to drive cancer and modulate immune pathways; previously, we demonstrated in keratinocytes that HPV 16 E6 and high expression of the endogenous host protein partner NFX1-123 led to the increased expression of multiple genes, including Notch1, secretory leukocyte peptidase inhibitor (SLPI), and retinoic acid early transcript 1G (RAET1G). The present study was conducted to determine if NFX1-123 was highly expressed in cervical cancer and if genes increased by NFX1-123 and 16E6 in keratinocytes were also increased in cervical cancers.Materials and methodsThe Cancer Genome Atlas (TCGA) database and The Human Protein Atlas database were used to compare relative mRNA and protein gene expression, respectively, in the normal cervix and cervical cancers. Formalin-fixed paraffin-embedded (FFPE) normal cervix and HPV 16 positive cervical cancer samples were analyzed for relative protein expression by immunohistochemical staining. Protein expression of a subset of regulated genes was quantified by Western blot of HPV positive and negative cell lines.ResultsImmunohistochemical staining of HPV 16 positive cervical dysplasias and cancers revealed high NFX1-123, Ki67, and Notch1 expression. NFX1 and NFX1L1 mRNA levels were increased in cervical cancers compared to normal cervix in the TCGA database. Fourteen genes previously identified as upregulated in keratinocytes with 16E6 and overexpressed NFX1-123 also had high mRNA expression and selected genes had high protein expression in cervical cancers and cell lines.ConclusionIn cervical cancer, NFX1-123 is highly expressed, and 16E6 and NFX1-123 together alter the expression of a wide set of genes. The involvement of these genes in cell proliferation, differentiation, invasion, and metastasis provides further insight into potential ways that HR HPVs promote cancer initiation and maintenance.

Project description:High-risk human papillomavirus (HPV) is a major risk factor for oral and pharyngeal cancers (OPCs), yet the detailed mechanisms by which HPV promotes OPCs are not understood. Forkhead box M1B (FoxM1B) is an oncogene essential for cell cycle progression and tumorigenesis, and it is aberrantly overexpressed in many tumors. We previously showed that FoxM1B was the putative target of an epithelial-specific transcription factor, Grainyhead-like 2 (GRHL2). In the current study, we demonstrate that HPV type 16 (HPV-16) E6 induces FoxM1B in human oral keratinocytes (HOKs) and tonsillar epithelial cells (TECs) in part through GRHL2. FoxM1B was barely detectable in cultured normal human oral keratinocytes (NHOKs) and progressively increased in immortalized HOKs harboring HPV-16 genome (HOK-16B) and tumorigenic HOK-16B/BaP-T cells. Retroviral expression of HPV-16 E6 and/or E7 in NHOKs, TECs, and hypopharyngeal carcinoma cells (FaDu) revealed induction of FoxM1B and GRHL2 by the E6 protein but not E7. Both GRHL2 and FoxM1B were strongly induced in the epidermis of HPV-16 E6 transgenic mice and HPV+ oral squamous cell carcinomas. Ectopic expression of FoxM1B led to acquisition of transformed phenotype in HOK-16B cells. Loss of FoxM1B by lentiviral short hairpin RNA vector or chemical inhibitor led to elimination of tumorigenic characteristics of HOK-16B/BaP-T cells. Luciferase reporter assay revealed that GRHL2 directly bound and regulated the FoxM1B gene promoter activity. Using epithelial-specific Grhl2 conditional knockout mice, we exposed wild-type (WT) and Grhl2 KO mice to 4-nitroquinolin 1-oxide (4-NQO), which led to induction of FoxM1B in the tongue tissues and rampant oral tumor development in the WT mice. However, 4-NQO exposure failed to induce tongue tumors or induction of FoxM1B expression in Grhl2 KO mice. Collectively, these results indicate that HPV-16 induces FoxM1B in part through GRHL2 transcriptional activity and that elevated FoxM1B level is required for oropharyngeal cancer development.

Dataset Information

Human papillomavirus type 16 E6 and NFX1-123 mislocalize immune signaling proteins and downregulate immune gene expression in keratinocytes.

Publications

Human papillomavirus type 16 E6 and NFX1-123 mislocalize immune signaling proteins and downregulate immune gene expression in keratinocytes.

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