SUMMARY Squamous cell carcinoma in the head and neck (HNSCC) is a common yet poorly understood cancer, with adverse clinical outcomes due to treatment resistance, recurrence, and metastasis. Putative cancer stem cells (CSCs) have been identified in HNSCC and BMI1 expression has been linked to these phenotypes, but optimal treatment strategies to overcome chemotherapeutic resistance and eliminate metastases have not yet been identified. Here, we show through lineage tracing and genetic ablation that BMI1+ CSCs mediate invasive growth and cervical lymph node metastasis in a mouse model of HNSCC. This model and primary human HNSCC samples contain highly tumorigenic, quiescent, and cisplatin-resistant BMI1+ CSCs, which exhibit increased AP-1 activity that drives invasive growth and metastasis of HNSCC. Inhibiting AP-1 or BMI1 sensitized tumors to cisplatin-based chemotherapy and eliminated lymph node metastases by targeting CSCs and the tumor bulk, suggesting potential regimens to overcome resistance to treatments and eradicate HNSCC metastasis.

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Purpose: Agents extracted from natural sources with antitumor property have attracted considerable attention from researchers and clinicians because of their safety, efficacy, and immediate availability. Degalactotigonin (DGT), extracted from Solanum nigrum L., has anticancer properties without serious side effects. Here, we explored whether DGT can inhibit the growth and metastasis of osteosarcoma.Experimental Design: MTT, colony formation, and apoptosis assays were performed to analyze the effects of DGT on osteosarcoma cell viability in vitro. The migration and invasion abilities were measured using a Transwell assay. Animal models were used to assess the roles of DGT in both tumor growth and metastasis of osteosarcoma. Gli1 expression and function were measured in osteosarcoma cells and clinical samples. After DGT treatment, Gli1 activation and the phosphorylation status of multiple cellular kinases were measured with a luciferase reporter and phospho-kinase antibody array.Results: DGT inhibited proliferation, induced apoptosis, and suppressed migration and invasion in osteosarcoma cells. DGT, injected intraperitoneally after tumor inoculation, significantly decreased the volume of osteosarcoma xenografts and dramatically diminished the occurrence of osteosarcoma xenograft metastasis to the lungs. Mechanistically, DGT inhibited osteosarcoma growth and metastasis through repression of the Hedgehog/Gli1 pathway, which maintains malignant phenotypes and is involved in the prognosis of osteosarcoma patients. DGT decreased the activity of multiple intracellular kinases that affect the survival of osteosarcoma patients, including GSK3b. In addition, DGT represses the Hedgehog/Gli1 pathway mainly through GSK3b inactivation.Conclusions: Our studies provide evidence that DGT can suppress the growth and metastasis of human osteosarcoma through modulation of GSK3b inactivation-mediated repression of the Hedgehog/Gli1 pathway.