Anticancer activity of cationic porphyrins in melanoma tumour-bearing mice and mechanistic in vitro studies

摘要

Background Porphyrin TMPyP4 (P4) and its C₁₄H₂₈-alkyl derivative (C14) are G-quadruplex binders and singlet oxygen (1O₂) generators. In contrast, TMPyP2 (P2) produces 1O₂ but it is not a G-quadruplex binder. As their photosensitizing activity is currently undefined, we report in this study their efficacy against a melanoma skin tumour and describe an in vitro mechanistic study which gives insights into their anticancer activity. Methods Uptake and antiproliferative activity of photoactivated P2, P4 and C14 have been investigated in murine melanoma B78-H1 cells by FACS, clonogenic and migration assays. Apoptosis was investigated by PARP-1 cleavage and annexin-propidium iodide assays. Biodistribution and in vivo anticancer activity were tested in melanoma tumour-bearing mice. Porphyrin binding and photocleavage of G-rich mRNA regions were investigated by electrophoresis and RT-PCR. Porphyrin effect on ERK pathway was explored by Western blots. Results Thanks to its higher lipophylicity C14 was taken up by murine melanoma B78-H1 cells up to 30-fold more efficiently than P4. When photoactivated (7.2?J/cm2) in B78-H1 melanoma cells, P4 and C14, but not control P2, caused a strong inhibition of metabolic activity, clonogenic growth and cell migration. Biodistribution studies on melanoma tumour-bearing mice showed that P4 and C14 localize in the tumour. Upon irradiation (660?nm, 193?J/cm2), P4 and C14 retarded tumour growth and increased the median survival time of the treated mice by ~50% (P Conclusions Porphyrins P4 and C14 impair the clonogenic growth and migration of B78-H1 melanoma cells and inhibit melanoma tumour growth in vivo . Evidence is provided that C14 acts through light-dependent (mRNA photocleavage) and light-independent (translation inhibition) mechanisms.