J Cancer 2017; 8(15):3014-3027. doi:10.7150/jca.21169 This issue
1. Department of Preventive and Public Oral Health, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Matsudo, Chiba 271-8587, Japan
2. Research Institute of Oral Health, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Matsudo, Chiba 271-8587, Japan
3. Department of Oral Health, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan
4. Department of Biochemistry and Molecular Biology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Matsudo, Chiba 271-8587, Japan
Background: Chemokines selectively attract and activate leukocytes and play roles in a variety of homeostatic and disease processes. Explore the biological properties of CXCL14 seems complicated due to unknown functional characteristics of CXCL14 in cancer.
Methods: To study the multistep process of oral cancer development, we analyzed oral samples spanning normalcy, dysplasia and cancer from multiple perspectives, revealing a cascade of progressive changes.
Results: CXCL14 protein was expressed in the cytoplasm adjacent to tumors. T classification (P<0.001), clinical stage (P=0.0013) and nodal metastasis (P=0.0035) were significantly associated with CXCL14 in relationships between CXCL14 expression levels and tumor and patient characteristics. Compared with non-tumor tissue, expression of the epidermal growth factor receptor (EGFR) gene was increased in dysplasia and was further sustained in cancer. Our data show an inverse relationship between CXCL14 and EGFR expression levels in tumor cells indicating that CXCL14 expression is beneficial for tumor suppression. To explore epigenetic regulation and the impact of CXCL14 on oral cancer, analysis of CpG islands methylation in the CXCL14 promoter region indicated that the abnormal hypermethylation of that promoter region in tumor cells and tissues is one of the mechanisms causing the reduced expression. Restoration of CXCL14 expression was induced by treatment with 5-aza-2′-deoxycytidine. Using in vivo mouse models, we demonstrate that the restoration of CXCL14 expression in irradiation-induced oral carcinoma cells induces the expression of Late Cornified Envelope (LCE) genes.
Conclusions: Our data suggest that LCE genes are a novel target of CXCL14 and are likely to have a tumor suppressor function through the modulation of CXCL14 expression. In conclusion, CXCL14 might play a pivotal role in the pathobiology of oral cancer, probably by regulating DNA methylation and leukocyte migration. The level of CXCL14 expression may be a valuable adjuvant parameter to predict the prognosis of patients with oral carcinoma and may be a potential therapeutic target.
Keywords: Chemokine, CXCL14, EGFR, DNA methylation, Irradiation, LCE