The growth inhibitory effect of human gingiva-derived mesenchymal stromal cells expressing interferon-β on tongue squamous cell carcinoma cells and xenograft model.

Background: Interferon-β (IFN-β) is a cytokine with pleiotropic cellular functions, including antiviral, antiproliferative, and immunomodulatory activities. IFN-β inhibits multiple tumor cell growth in vitro. However, the contradiction between the therapeutic dose of IFN-β and its maximally tolerated dose is still inextricable in vivo. Human gingiva-derived mesenchymal stromal cells (GMSCs) represent promising vehicles for cancer gene therapy. This study evaluated the potential of GMSCs genetically engineered to produce IFN-β as a targeted gene delivery system to treat tongue squamous cell carcinoma (TSCC) in vitro and in vivo.

Methods: A lentiviral vector encoding IFN-β was constructed and transfected into GMSCs to obtain IFN-β gene-modified GMSCs (GMSCs/IFN-β). Enzyme-linked immunosorbent assay (ELISA) was used to measure the IFN-β concentration in conditioned medium (CM) from GMSCs/IFN-β. The Cell Counting Kit-8 (CCK8), colony formation assay, and flow cytometry were used to detect the effects of GMSCs/IFN-β on TSCC cell line CAL27 cell growth and apoptosis in vitro. TSCC xenograft model was developed by subcutaneous injection of CAL27 cells into BALB/c nude mouse, and the role of intravenously injected GMSCs/IFN-β in engrafting in TSCC and controlling tumor progression was measured in vivo.

Results: GMSCs/IFN-β expressed a high level of IFN-β. Both CCK8 and colony forming assay showed that GMSCs/IFN-β significantly inhibited the proliferation of CAL27 cells compared with the GMSCs, GMSCs/vector, or DMEM group. Flow cytometry analysis demonstrated that the CAL27 cell apoptosis rate was higher in the GMSCs/IFN-β group than in the other three groups. The in vivo experiment revealed that GMSCs/IFN-β engrafted selectively in TSCC xenograft and expressed a high level of IFN-β. There were smaller tumor volume and lower number of Ki67-positive cells in the GMSCs/IFN-β group than in the GMSCs, GMSCs/vector, or phosphate-buffered saline (PBS) group. Interestingly, GMSCs and GMSCs/vector also presented the potential of CAL27 cell growth inhibition in vitro and in vivo, although such an effect was weaker than GMSCs/IFN-β.

Conclusions: GMSCs/IFN-β inhibits the proliferation of TSCC cells in vitro and in vivo. These results provide evidence that delivery of IFN-β by GMSCs may be a promising approach to develop an effective treatment option for TSCC therapy.