Human telomeres were one of the first discovered and characterized sequences forming quadruplex structures. Association of these structures with oncogenic and
tumor suppressor proteins suggests their important role in
cancer development and
therapy efficacy. Since cationic
porphyrin TMPyP4 is known as G-quadruplex stabilizer and
telomerase inhibitor, the aim of the study was to analyze the anticancer properties of this compound in two different human
breast-cancer MCF7 and MDA-MB-231 cell lines. The cytotoxicity of
TMPyP4 alone or in combination with
doxorubicin was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-
diphenyl tetrazolium bromid) and clonogenic assays, and the cell-cycle alterations were analyzed by flow cytometry.
Telomerase expression and activity were evaluated using qPCR and telomeric repeat amplification protocol (TRAP) assays, respectively. The contribution of G-quadruplex inhibitor to
protein pathways engaged in cell survival, DNA repair, adhesion, and migration was performed using immunodetection. Scratch assay and functional assessment of migration and cell adhesion were also performed. Consequently, it was revealed that in the short term,
TMPyP4 neither revealed cytotoxic effect nor sensitized MCF7 and MDA-MB-231 to
doxorubicin, but altered
breast-cancer cell adhesion and migration. It suggests that
TMPyP4 might substantially contribute to a significant decrease in
cancer cell dissemination and, consequently,
cancer cell survival reduction. Importantly, this effect might not be associated with telomeres or
telomerase.