Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
Center of Excellence in Oral and Maxillofacial Biology, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
Eur J Oral Sci. 2021 Jun;129(3):e12775. doi: 10.1111/eos.12775. Epub 2021 Mar 30.
The aims of this study were to determine the functional roles of the transmembrane glycoprotein, Disintegrin and metalloproteinase domain-containing protein 9 (ADAM 9), in the phosphorylation of epidermal growth factor receptor (EGFR) and AKT and in the aggressiveness of oral cancer cells. Immunohistochemistry and immunoblotting were conducted to determine expression of ADAM 9 and the levels of EGFR phosphorylated at the tyrosine 1173 residue (p-EGFR ) and AKT phosphorylated at the serine 473 residue (p-AKT ) in oral cancer tissues and in the oral cancer cell lines HN5, HN6, HN15, and HN008. Small interfering RNA (siRNA) was used to inhibit expression of ADAM9 mRNA, and thus production of ADAM9 protein, in oral cancer cells. ADAM9-knockdown cells were examined for p-EGFR and p-AKT levels and used for cell proliferation and invasion assays. A positive correlation among overexpression of ADAM 9, p-EGFR , and p-AKT was found in oral cancer tissues. These biomolecules were also overexpressed in HN6 and HN15 cell lines. Expression of ADAM9 in HN6 and HN15 cells was statistically significantly inhibited by siRNA against ADAM9 mRNA (siADAM9) compared with the negative-control siRNA (scramble). The levels of p-AKT , but not those of p-EGFR , were statistically significantly blocked by siADAM9. Although the proliferation rates of ADAM9 knocked-down HN6 and HN15 cells did not differ from those of cells exposed to scramble, a statistically significant decrease in cell invasion was found in these ADAM9-silenced cells. These results suggest a functional role of the ADAM 9/AKT signaling pathway in oral cancer cell invasion, which may be beneficial as a therapeutic target of oral cancer.
本研究旨在确定跨膜糖蛋白、解整合素和金属蛋白酶结构域蛋白 9（ADAM9）在表皮生长因子受体（EGFR）和 AKT 磷酸化以及口腔癌细胞侵袭性中的功能作用。采用免疫组织化学和免疫印迹法检测口腔癌组织和口腔癌细胞系 HN5、HN6、HN15 和 HN008 中 ADAM9 的表达以及酪氨酸 1173 残基磷酸化的 EGFR（p-EGFR）和丝氨酸 473 残基磷酸化的 AKT（p-AKT）水平。用小干扰 RNA（siRNA）抑制口腔癌细胞中 ADAM9 mRNA 的表达，从而抑制 ADAM9 蛋白的产生。检测 ADAM9 敲低细胞中 p-EGFR 和 p-AKT 的水平，并进行细胞增殖和侵袭实验。结果发现，口腔癌组织中 ADAM9 过表达与 p-EGFR 和 p-AKT 呈正相关。HN6 和 HN15 细胞系中也过表达这些生物分子。与阴性对照 siRNA（scramble）相比，针对 ADAM9 mRNA 的 siRNA（siADAM9）可显著抑制 HN6 和 HN15 细胞中 ADAM9 的表达。p-AKT 水平被 siADAM9 显著阻断，但 p-EGFR 水平未被阻断。虽然 ADAM9 敲低的 HN6 和 HN15 细胞的增殖率与暴露于 scramble 的细胞没有差异，但在这些 ADAM9 沉默的细胞中发现细胞侵袭显著减少。这些结果表明 ADAM9/AKT 信号通路在口腔癌细胞侵袭中具有功能作用，可能作为口腔癌的治疗靶点有益。
