Long non-coding RNA PP7080 enhances cancer stemness and tumorigenic features in oral cancer

Emerging evidence has shown that various failures in cancer therapy, such as drug resistance, metastasis, and cancer relapse are attributed to cancer stem cells (CSCs). Also, growing attention has been paid to the regulation of non-coding RNAs in cancer stemness. Here, we aimed to investigate the impact of lncRNA PP7080 on cancer stemness in oral squamous cell carcinomas.

PP7080 expression was assessed in ALDH1⁺ and ALDH1^- cells sorted from oral squamous cell carcinoma cell lines using qRT-PCR. PP7080 was silenced in ALDH1⁺ SAS cells, and the effects on stemness characteristics, including ALDH1 activity, cell migration, colony formation, CD44 and Oct4 expression, and the expression of drug resistance-related markers ABCG2 and Bmi-1, were examined. The interaction between PP7080 and miR-601 was validated using a luciferase reporter assay. Rescue experiments were performed by inhibiting miR-601 in PP7080-silenced cells using apoptosis analysis. PP7080 expression in HNSCC was analyzed using the TCGA-HNSCC database.

Our results showed that PP7080 was significantly overexpressed in oral cancer tissues and positively correlated with stemness markers. The phenotypic and flow cytometry assays demonstrated that suppression of PP7080 reduced the migratory and colony-forming aibilities, cancer stemness features, and self-renewal abilities in oral CSCs. Furthermore, we demonstrated that PP7080 may enhance cancer stemness features by counteracting the tumor-suppressive effect of miR-601.

Targeting PP7080 may offer a promising therapeutic strategy for oral cancer by reducing cancer stemness.