目的：探讨微小RNA-6803 （miR-6803）及其宿主基因蛋白磷酸酶6调节亚单位1 （protein phosphatase 6 regulation sub-unit 1, PPP6R1）在食管鳞状细胞癌（ESCC）中的表达和PPP6R1基因启动子区甲基化状态及其在ESCC发生及发展中的作用。方法： 采用2013年至2014年间河北医科大学第四医院生物标本库的72例ESCC手术患者癌组织及对应的癌旁组织标本，用实时荧光定量PCR法检测miR-6803和PPP6R1在ESCC组织及其癌旁组织和DNA甲基化转移酶抑制剂5-氮杂-2’-脱氧胞苷（5-Aza-dC）处理前后的ESCC细胞株TE1、TE13、Eca109、T.TN、Kyse170中的表达水平。用甲基化特异性PCR（MSP）法检测ESCC细胞系和组织及其癌旁组织中PPP6R1的甲基化状态，分析其与患者临床病理特征的关系。 结果： ESCC组织中miR-6803和PPP6R1的表达水平显著低于癌旁组织0.318±0.156，0.408±0.177 vs 1.000±0.001，均P<0.05），miR-6803表达水平与淋巴结转移、组织分化程度及TNM分期密切相关(均P<0.05)；PPP6R1表达水平与TNM分期和组织学分化程度密切相关（均P＜0.05）。ESCC组织中miR-6803和PPP6R1基因的表达具有显著相关性（P<0.05）。ESCC组织中PPP6R1的启动子区甲基化率显著高于癌旁组织（56.94% vs 36.11%，P＜0.05），并与TNM分期和组织学分化程度密切相关（均P＜0.05）,miR-6803 和 PPP6R1基因的低表达与PPP6R1启动子区甲基化明显相关（P＜0.05）。经5-Aza-dC处理后，5种ESCC细胞中miR-6803和PPP6R1的表达均升高，并且TE1、TE13、Kyse170细胞中PPP6R1基因甲基化程度降低，非甲基化程度增加，其余2种细胞中PPP6R1基因均表现为非甲基化状态。 结论： miR-6803及其宿主基因PPP6R1的低表达可能与ESCC的发生发展密切相关，其启动子区甲基化可能是miR-6803和PPP6R1表达沉默的机制之一。

Objective: To investigate the expression of microRNA-6803(miR-6803) and its host gene PPP6R1 in esophageal squamous cell carcinoma (ESCC) and the role of promoter methylation status of PPP6R1 in the tumori-genisis and progression of ESCC. Methods: ESCC tissues and corresponding para-cancerous tissues from 72 cases of ESCC patients stored in the bio-specimen base of the Fourth Hospital Affiliated to Heibei Medical University dur-ing 2013 and 2014 were collected for this study.Real-time fluorescence quantitative PCR (qPCR) was used to detect the expression of miR- 6803/PPP6R1 in collected tissues and in ESCC cell lines (TE1, TE13, Eca109, T.TN,Kyse170) treated or untreated with DNA methyl-transferase inhibitor 5-aza-2’-detoxycytidine (5-Aza-dC). Methyla-tion specific PCR (MSP) method was used to detect the methylation status of PPP6R1 in esophageal cancer cell lines and collected tissues, respectively. Results: The relative expressions of miR-6803 and PPP6R1 in ESCC tis-sues were significantly reduced compared to correspondingtissues (0.318±0.156, 0.408±0.177 vs 1.000±0.001, all P<0.05), and expression of miR-6803 was associated with lymph node metastasis, TNM stage and pathological differ-entiation (all P<0.05); The expression of PPP6R1 was associated with TNM stage and pathological differentiation (all P<0.05). There was a significant correlation between the relative expression of miR-6803 and PPP6R1 in ESCC tissues (P<0.05).The promoter methylation frequency of PPP6R1 in ESCC tissues was significantly higher than that in corresponding normal tissues (56.94% vs 36.11%, P<0.05), and was also associated with TNM stage and patho-logical differentiation (all P<0.05). The low expression of miR-6803/PPP6R1 was significantly correlated with pro-moter methylation of PPP6R1 in ESCC tissues (P<0.05). The relative expression level of miR-6803 and PPP6R1 in 5 ESCC cell lines was enhanced after the treatment with 5-Aza-dC. After treatment with 5-Aza-dC, the methylation level of PPP6R1 was decreased in TE1, TE13, Kyse170 cells, while complete unmethylation of PPP6R1 was detect-ed in other two cell lines. Conclusion: Aberrant low expression of miR-6803 and its host gene PPP6R1 are closely related to the occurrence and development of ESCC, and promoter methylation may be one of the mechanisms for inactivation of miR-6803/PPP6R1 in ESCC.

国家自然科学基金资助项目（No.81572441）；河北省医学科学研究重点课题（No.20170700，No.20170701）