Calcitriol treatment improves methyl aminolaevulinate-based photodynamic therapy in human squamous cell carcinoma A431 cells.
BACKGROUND
Photodynamic therapy (PDT) using methyl aminolaevulinate (MAL) provides a new, approved method for treatment of skin cancer and its precursors. However, MAL-based PDT is not very efficient for poorly differentiated skin carcinoma. Thus, novel strategies to enhance the PDT effect are needed.


OBJECTIVE
In order to improve the efficacy of MAL-based PDT, we investigated the effect of adding calcitriol, a prodifferentiation hormone, to human squamous cell carcinoma A431 cells in vitro.


METHODS
A short course (24 h) of calcitriol pretreatment was applied in A431 cells, and, subsequently, MAL-induced protoporphyrin IX (PpIX) was measured.


RESULTS
Calcitriol pretreatment of the cells elevated their PpIX levels. Furthermore, the cell damage after exposure to blue light was significantly higher in calcitriol-treated cells. Increased photoinactivation correlated with higher levels of PpIX in the calcitriol-pretreated cells.


CONCLUSIONS
Calcitriol enhances MAL-based PDT in A431 cells.
Department of Radiation Biology, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Montebello, Oslo 0310, Norway.
E
E
Cicarma
M
M
Tuorkey
A
A
Juzeniene
L-W
LW
Ma
J
J
Moan
D000622:Aminolevulinic Acid / Q000031:analogs & derivatives* / Q000378:metabolism / Q000627:therapeutic use; D002117:Calcitriol / Q000494:pharmacology*; D002280:Basal Cell Carcinoma / Q000188:drug therapy* / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000378:metabolism* / Q000627:therapeutic use; D011524:Protoporphyrins / Q000096:biosynthesis*; D014410:Tumor Stem Cell Assay
D017319:Photosensitizing Agents; D011524:Protoporphyrins; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D002117:Calcitriol