Table 1.
Photodynamic therapy (PDT) resistance mechanisms.
| Proposed Mechanism(s) | Cell Line | Photosensitizer(s) | Reference |
|---|---|---|---|
| MDR Mediated drug efflux * | P388/ADR murine leukemia | Copper benzochlorin iminium salt, a cationic PS | [41] |
| ABCG2 associated drug efflux * | NCI-H1650 MX50 bronchoalveolar carcinoma | Pyropheophorbide | [42,43,44] |
| Chlorin e6 | |||
| PpIX from 5-aminolevulinic acid (ALA) | |||
| Endocytic vesicle localization of TPPS2a | MES-SA/Dx5 cells | Disulfonated meso-tetraphenylporphine (TPPS2a) | [45] |
| Modulation of the PS uptake and/or subcellular localization as well as changes in mitochondrial size and function | RIF-1 fibrosarcoma | Photofrin II | [46,47,48] |
| Polyhematoporphyrin (PHP) | |||
| Zinc (II) pyridinium-substituted phthalocyanine (ZnPCP) | |||
| Alterations in the enzymes of the heme pathway that produces PpIX | murine mammary adenocarcinoma | 5-aminolevulinic acid (ALA) | [49] |
| Attenuation of light in tissue LD | human glioma spheroids | 5-aminolevulinic acid (ALA) | [50] |
| Delayed apoptotic response sp | P388 murine leukemia | tin octaethylpurpurin amidine (SnOPA) | [51] |
* Also associated with chemotherapy resistance, sp signaling pathways, LD light-dose dependent resistance.