Purpose

Persistent infection with high-risk human papillomavirus (HR-HPV) is thought to play a prominent role in the initiation and progression of almost all cases of cervical cancer. Previously, we and others found that microRNA 34a (miR-34a) may be regulated by HR-HPV E6 to contribute to the development of cervical cancer. Here, we aimed to identify the oncogenic potential and clinical significance of a known miR-34a target, WNT1, in cervical squamous cell carcinoma (SCC) development and to investigate the associated mechanisms underlying cervical SCC cell proliferation and invasion.

Methods

WNT1 and miR-34a expression levels were assessed in primary cervical lesions using immunohistochemistry and qRT-PCR, respectively. The cellular effects and the expression of its associated genes were examined in cervical SCC-derived Siha and Caski cells after siRNA-WNT1 (downregulation) or miR-34a mimic (upregulation) treatment. A cervical SCC xenograft mouse model was used to investigate the in vivo effects of miR-34a overexpression. HPV-16 E6/E7 expression was inhibited by gene promoter siRNA targeting, after which the levels of miR-34a and WNT1 were examined.

Results

WNT1 protein upregulation was found to be associated with a poor prognosis in cervical SCC patients. In vitro assays in Siha and Caski cells revealed that WNT1 downregulation decreased cell proliferation and invasion, inhibited WNT/β-catenin activation and affected the expression of E-cadherin and P-cadherin. MiR-34a upregulation resulted in decreased WNT1 expression. An inverse correlation between miR-34a and WNT1 expression was also observed in primary cervical SCC tissues. In addition, we found that MiR-34a could regulate an E-cadherin to P-cadherin switch (E-P cadherin switch) to inhibit cell proliferation and tumorigenesis in vitro and in vivo via inactivation of the WNT1/β-catenin pathway. Finally, we found that decreased HPV-16 E6/E7 expression resulted in miR-34a upregulation and WNT1 downregulation in Siha and Caski cells.

Conclusions

From our results we conclude that WNT1, as a target of miR-34a, can promote cervical SCC cell proliferation and invasion by induction of an E-P cadherin switch via the WNT1/β-catenin pathway. Our results may provide new options for the treatment of patients with cervical SCC.

中文翻译：

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WNT1是miR-34a的靶标，通过经由WNT /β-catenin途径诱导EP钙粘蛋白开关，促进宫颈鳞状细胞癌的增殖和侵袭。

目的

人们认为，高危人乳头瘤病毒（HR-HPV）的持续感染在几乎所有宫颈癌病例的发生和发展中都起着重要作用。先前，我们和其他人发现，microRNA 34a（miR-34a）可能受HR-HPV E6调节，从而有助于宫颈癌的发展。在这里，我们旨在确定已知的miR-34a靶标WNT1在宫颈鳞状细胞癌（SCC）发育中的致癌潜力和临床意义，并研究宫颈SCC细胞增殖和侵袭的相关机制。

方法

使用免疫组织化学和qRT-PCR分别评估原发性宫颈病变中的WNT1和miR-34a表达水平。在siRNA-WNT1（下调）或miR-34a模拟（上调）处理后，在子宫颈SCC衍生的Siha和Caski细胞中检查了细胞效应及其相关基因的表达。宫颈SCC异种移植小鼠模型用于研究miR-34a过表达的体内效应。HPV-16 E6 / E7表达被基因启动子siRNA靶向抑制，此后检测miR-34a和WNT1的水平。

结果

发现WNT1蛋白上调与宫颈SCC患者预后不良有关。在Siha和Caski细胞中进行的体外分析表明，WNT1下调降低了细胞的增殖和侵袭，抑制了WNT /β-catenin的活化，并影响了E-cadherin和P-cadherin的表达。MiR-34a上调导致WNT1表达降低。在原发性宫颈鳞癌组织中也观察到了miR-34a和WNT1表达之间的负相关。此外，我们发现MiR-34a可以通过失活WNT1 /β-catenin途径在体外和体内将E-cadherin调节为P-cadherin开关（EP cadherin开关），从而抑制细胞增殖和肿瘤发生。最后，我们发现在Siha和Caski细胞中HPV-16 E6 / E7表达降低导致miR-34a上调和WNT1下调。

结论

根据我们的结果，我们得出结论，作为miR-34a的靶标，WNT1可通过WNT1 /β-catenin途径诱导EP钙黏着蛋白开关来促进宫颈SCC细胞增殖和侵袭。我们的结果可能为宫颈SCC患者的治疗提供新的选择。