Tumor-Suppressive MicroRNA-216b Binds to TPX2, Activating the p53 Signaling in Human Cutaneous Squamous Cell Carcinoma

Dysregulation of microRNAs (miRNAs) is acknowledged in human cutaneous squamous cell carcinoma (cSCC). We hereby evaluated the ability of miRNA-216b (miR-216b) to impact human cSCC. cSCC tissues with corresponding adjacent normal tissues were collected from 40 patients diagnosed with cSCC where the expression pattern of miR-216b and targeting protein for Xenopus kinesin-like protein 2 (TPX2) was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot analysis. A431 cells were transfected with miR-216b mimic, miR-216b inhibitor, or short interfering RNA against TPX2 to evaluate cell proliferation, invasion, migration, and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, scratch test, Transwell assay, and flow cytometry. TPX2 was highly expressed in cSCC tissues while miR-216b was poorly expressed in association with tumor differentiation, lymph node metastasis, and tumor node metastasis staging in patients with cSCC. In response to overexpressed miR-216b or silenced TPX2, cSCC cell proliferation, invasion, and migration were suppressed and apoptosis was stimulated, along with activated p53 signaling. Thus, upregulated miR-216b was capable of promoting apoptosis and inhibiting proliferation, invasion, and migration of cSCC cells by downregulating TPX2 through activation of the p53 signaling, highlighting a novel biomarker for novel treatment modalities against cSCC.