title: Aberrant GRK6 promoter methylation is associated with poor prognosis in hypopharyngeal squamous cell carcinoma.
abstract: Hypopharyngeal squamous cell carcinoma (HSCC) is one of the most common head and neck cancers with high invasiveness and poor prognosis. To identify targeted therapeutics against metastasis, a better understanding of the regulation of HSCC cell invasion is needed. In recent years, G protein-coupled receptor kinases (GRKs) have been implicated in cancer metastasis through phosphorylation of the activated form of G protein coupled receptors (GPCRs). However, there is little information regarding GRKs expression in HSCC. In the present study, we examined GRK6 expression in HSCC and also assessed the possible cause of its aberrant expression, as well as its clinical significance. Real-time quantitative PCR (qPCR) and western blotting were performed to analyze the expression of GRK6 in HSCC tissues and corresponding non-malignant tissues. Subsequently, paired HSCC and corresponding non-malignant tissues were evaluated for the methylation status of GRK6 gene promoter using methylation-specific PCR (MSP). Furthermore, we investigated the methylation status and the clinicopathological significance of GRK6 in 45 paired HSCC and corresponding non-malignant tissues. The suppression of GRK6 in hypopharyngeal cell line FaDu by GRK6-shRNA lentivirus transfection was utilized to detect the role of GRK6 in hypopharyngeal cancer progression. Our results showed that the expression of GRK6 mRNA and protein was significantly lower in HSCC than in corresponding adjacent non-tumor tissues, and this downregulation was found to be in accordance with aberrant methylation of the gene. Hypermethylation of the gene was observed in 77.8% (35/45) of the HSCC tissues, while it was found in only 42.2% (19/45) of the corresponding non-malignant tissues. GRK6 methylation was related to depth of tumor invasion and TNM stage. Upon treatment with 5-aza-2'-deoxycytidine, GRK6 expression was upregulated in FaDu cells, and cell invasion was signinficantly inhibited. Furthermore, the suppression of GRK6 by shRNA transfection enhanced FaDu cells invasion. Our results indicate that the aberrant methylation of GRK6 gene promoter may underlie its downregulation in HSCC, and may play an important role in the metastasis of HSCC.
authors.affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, General Hospital of Jinan Military Region, Jinan, Shandong 250031, P.R. China.
authors.forename: Jianqiu
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
authors.forename: Zhenxin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
authors.forename: Yiwen
authors.initials: Y
authors.lastname: You
authors.affiliation: Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wang
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D015536:Down-Regulation; D054768:G-Protein-Coupled Receptor Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D000077209:Decitabine; D054768:G-Protein-Coupled Receptor Kinases; C089176:G-protein-coupled receptor kinase 6; D001374:Azacitidine