Grainyhead-like 2 (GRHL2) is one of the three mammalian homologues of Drosophila Grainyhead involved in epithelial morphogenesis. We recently showed that GRHL2 also controls normal epithelial cell proliferation and differentiation. In this study, we investigated the role of GRHL2 in oral carcinogenesis and the underlying mechanism. GRHL2 expression was elevated in cells and tissues of oral squamous cell carcinomas (OSCCs) compared with normal counterparts. Knockdown of GRHL2 resulted in the loss of in vivo tumorigenicity, cancer stemness and epithelial phenotype of oral cancer cells. GRHL2 loss also inhibited oral cancer cell proliferation and colony formation. GRHL2 regulated the expression of miR-200 family and Octamer-binding transcription factor 4 (Oct-4) genes through direct promoter DNA binding. Overexpression of miR-200 genes in the oral cancer cells depleted of GRHL2 partially restored the epithelial phenotype, proliferative rate and cancer stemness, indicating that miR-200 genes in part mediate the functional effects of GRHL2. Taken together, this study demonstrates a novel connection between GRHL2 and miR-200, and supports protumorigenic effect of GRHL2 on OSCCs.

This limited study suggested that the predictability of augmented bone volume in staged alveolar ridge augmentation using titanium micromesh was not sufficient to expect an ideal and planned implant placement. The success was influenced by the distance of the augmentation site and the infection of the graft material, which were associated with moderate to severe vertical ridge resorption and/or mechanical and functional loading on the surgical site.

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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.