The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei_MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
Oral Histopathology Department, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
Cancer Sci. 2021 Jan;112(1):117-132. doi: 10.1111/cas.14691. Epub 2020 Nov 9.
Homeodomain-interacting protein kinase 2 (HIPK2), a well-known tumor suppressor, shows contradictory expression patterns in different cancers. This study was undertaken to clarify HIPK2 expression in oral squamous cell carcinoma (OSCC) and to reveal the potential mechanism of HIPK2 involvement in OSCC metastasis. Two hundred and four OSCC tissues, together with paired adjacent normal epithelia, dysplastic epithelia, and lymph node metastasis specimens, were collected to profile HIPK2 expression by immunohistochemical staining. High throughput RNA-sequencing was used to detect the dysregulated signaling pathways in HIPK2-deficient OSCC cells. Transwell assay and lymphatic metastatic orthotopic mouse model assay were undertaken to identify the effect of HIPK2 on tumor invasion. Western blotting and luciferase reporter assay were used to examine the HIPK2/P53/E-cadherin axis in OSCC. Nuclear delocalization of HIPK2 was observed during oral epithelial cancerization progression and was associated with cervical lymph node metastasis and poor outcome. Depletion of HIPK2 promoted tumor cell invasion in vitro and facilitated cervical lymph node metastasis in vivo. According to mRNA-sequencing, pathways closely related to tumor invasion were notably activated. Homeodomain-interacting protein kinase 2 was found to trigger E-cadherin expression by mediating P53, which directly targets the CDH1 (coding E-cadherin) promoter. Restoring P53 expression rescued the E-cadherin suppression induced by HIPK2 deficiency, whereas rescued cytoplasmic HIPK2 expression had no influence on the expression of E-cadherin and cell mobility. Together, nuclear delocalization of HIPK2 might serve as a valuable negative biomarker for poor prognosis of OSCC and lymph node metastasis. The depletion of HIPK2 expression promoted OSCC metastasis by suppressing the P53/E-cadherin axis, which might be a promising target for anticancer therapies.
同源结构域相互作用蛋白激酶 2（HIPK2）是一种众所周知的肿瘤抑制因子，在不同的癌症中表现出矛盾的表达模式。本研究旨在阐明 HIPK2 在口腔鳞状细胞癌（OSCC）中的表达，并揭示 HIPK2 参与 OSCC 转移的潜在机制。收集了 204 例 OSCC 组织，以及配对的相邻正常上皮、发育不良上皮和淋巴结转移标本，通过免疫组织化学染色分析 HIPK2 的表达情况。高通量 RNA 测序用于检测 HIPK2 缺陷型 OSCC 细胞中失调的信号通路。Transwell 测定和淋巴转移原位小鼠模型测定用于确定 HIPK2 对肿瘤侵袭的影响。Western blot 和荧光素酶报告基因测定用于检测 OSCC 中的 HIPK2/P53/E-钙黏蛋白轴。在口腔上皮癌变进展过程中观察到 HIPK2 的核定位缺失，与颈淋巴结转移和不良预后相关。HIPK2 的缺失促进了肿瘤细胞在体外的侵袭，并促进了体内颈淋巴结的转移。根据 mRNA 测序，与肿瘤侵袭密切相关的途径被明显激活。同源结构域相互作用蛋白激酶 2 通过介导 P53 触发 E-钙黏蛋白的表达，P53 直接靶向 CDH1（编码 E-钙黏蛋白）启动子。恢复 P53 表达可挽救 HIPK2 缺陷引起的 E-钙黏蛋白抑制，而挽救细胞质 HIPK2 表达对 E-钙黏蛋白表达和细胞迁移能力没有影响。总之，HIPK2 的核定位缺失可能成为 OSCC 预后不良和淋巴结转移的有价值的阴性生物标志物。HIPK2 表达的缺失通过抑制 P53/E-钙黏蛋白轴促进 OSCC 转移，这可能是一种有前途的抗癌治疗靶点。
