Connexin43 peptide, TAT-Cx43266-283, selectively targets glioma cells, impairs malignant growth and enhances survival in mouse models in vivo.

Background. Malignant gliomas are the most frequent primary brain tumors and remain among the most incurable cancers. Although the role of the gap junction protein, connexin43 (Cx43), has been deeply investigated in malignant gliomas, no compounds have been reported with the ability to recapitulate the tumor suppressor properties of this protein in in vivo glioma models. Methods. TAT-Cx43(266-283) a cell-penetrating peptide which mimics the effect of Cx43 on c-Src inhibition, was studied in orthotopic immunocompetent and immunosuppressed models of glioma. The effects of this peptide in brain cells were also analyzed. Results. While glioma stem cell malignant features were strongly affected by TAT-Cx43(266-283), these properties were not significantly modified in neurons and astrocytes. Intraperitoneally administered TAT-Cx43(266-283) decreased the invasion of intracranial tumors generated by GL261 mouse glioma cells in immunocompetent mice. When human glioma stem cells were intracranially injected with TAT-Cx43(266-283) into immunodeficient mice, there was reduced expression of the stemness markers nestin and Sox2 in human glioma cells at 7 days post-implantation. Consistent with the role of Sox2 as a transcription factor required for tumorigenicity, TAT-Cx43(266-283) reduced the number and stemness of human glioma cells at 30 days post-implantation. Furthermore, TAT-Cx43(266-283) enhanced the survival of immunocompetent mice bearing gliomas derived from murine glioma stem cells. Conclusion. TAT-Cx43(266-283) reduces the growth, invasion, and progression of malignant gliomas and enhances the survival of glioma-bearing mice without exerting toxicity in endogenous brain cells, which suggests that this peptide could be considered as a new clinical therapy for high-grade gliomas.