P16INK4A和PTEN在高危型HPV相关宫颈癌组织中的表达及意义

背景与目的:高危型人乳头状瘤病毒(high-risk human papillomavirus,HR-HPV)是宫颈癌最主要的致病因素,目前研究发现,在宫颈上皮癌变过程中,P16INK4A的异常表达和HR-HPV感染密切相关;同时,另一抑癌基因PTEN也参与了宫颈上皮肿瘤的形成.本研究旨在探讨宫颈上皮癌变过程中P16INK4A、PTEN表达与HR-HPV感染的关系及其意义.方法:应用免疫组织化学方法检测P16INK4A蛋白和PTEN蛋白在30例正常宫颈组织、11例原位癌、24例宫颈浸润癌组织中的表达.用第二代杂交捕获法(HC-2)检测每一病例的13种HR-HPV DNA.结果:HR-HPV和P16INK4A阳性率浸润癌组(91.7%、87.5%)和原位癌组(90.9%、81.8%)都明显高于正常宫颈组(30.0%、6.7%),差异有统计学意义(P＜0.001).P16INK4A过表达(中、强阳性)和HR-HPV阳性同时出现有30例,其中原位癌组9例,浸润癌组21例;两者同时阴性有23例,其中正常宫颈组20例,原位癌组1例,浸润癌组2例.相关性分析结果显示,HR-HPV感染与P16INK4A表达呈正相关(rs=0.690,P＜0.001).26例PTEN中、强阳性表达均在正常宫颈组,其阳性率在浸润癌组(37.5%)和原位癌组(36.4%)明显低于正常宫颈组(83.3%),差异有统计学意义(P＜0.01).相关性分析证实,HR-HPV感染与PTEN表达的相关性无统计学意义(rs=-0.174,P=0.167).结论:在HR-HPV感染的宫颈癌中,P16INK4A出现过表达,其蛋白的肿瘤抑制功能不明显;PTEN独立于HR-HPV途径,以其功能下调促进宫颈癌的发生、发展.

Expression and significance of P16INK4A and PTEN in high-risk human papillomavirus-related cervical cancer

BACKGROUND & OBJECTIVE: High-risk human papillomavirus (HR-HPV) is the most important etiologic factor for cervical cancer. Recent studies have revealed that abnormal expression of tumor suppressor gene P16INK4A is closely associated with HR-HPV infection during carcinogenesis of cervical epithelium. Tumor suppressor gene PTEN is also involved in cervical tumorigenesis. This study was to investigate the correlations of HR-HPV infection to P16INK4A and PTEN expression and its clinical significance in the carcinogenesis of cervical epithelium. METHODS: The expression of P16INK4A and PTEN in 30 specimens of normal cervical tissues, 11 specimens of cancer in situ (CIS), and 24 specimens of invasive cervical carcinoma (ICC) was detected by SP immunohistochemistry; 13 types of HR-HPV DNA in these cases were detected by Hybrid Capture 2 (HC-2) assay. RESULTS: The positive rates of HR-HPV and P16INK4A were significantly higher in ICC and CIS than in normal tissues (91.7% and 90.9% vs. 30.0%, P<0.001; 87.5% and 81.8% vs. 6.7%, P<0.001). Both HR-HPV DNA and P16INK4A overexpression(moderate or strong expression) were observed simultaneously in 21 specimens of ICC and 9 specimens of CIS; they were simultaneously negative in 20 specimens of normal cervical tissues and 1 specimen of CIS and 2 specimens of ICC. Overexpression of P16INK4A was positively correlated to HR-HPV infection in cervical cancer (rs = 0.690, P<0.001). PTEN was moderately or strongly expressed in 26 specimens of normal cervical tissues. The positive rate of PTEN was significantly lower in ICC and CIS than in normal cervical tissues (37.5% and 36.4% vs. 83.3%, P<0.01). No obvious relationship between PTEN and HR-HPV was found (rs = -0.174, P = 0.167). CONCLUSIONS: P16INK4A is overexpressed in HR-HPV-infected cervical cancer, but its tumor suppressor action might be inhibited. In contrast, the functional down-regulation of PTEN contributes to cervical tumorigenesis through HR-HPV-independent mechanism.