Enhancement of photodynamic effect in normal rat keratinocytes by treatment with 1,25 dihydroxy vitamin D3

Vitamin D and Vitamin D3 Supplementation during Photodynamic Therapy: A Review

Photodynamic therapy is an unconventional yet increasingly common method of treating dermatological diseases and cancer that is implemented more often in adults than in children. Current clinical uses include treatment of actinic keratosis, superficial basal cell carcinomas, and acne. Despite its high efficiency, photodynamic therapy support supplements have recently been reported in the literature, including calcitriol (1,25-dihydroxycholecalciferol), the active form of vitamin D, and vitamin D3 cholecalciferol. In clinical trials, photodynamic therapy enhanced with vitamin D or D3 supplementation has been reported for treatment of squamous cell skin cancers, actinic keratosis, and psoriasis. Experimental research on the effect of photodynamic therapy with vitamin D or D3 has also been carried out in breast cancer cell lines and in animal models. The aim of this review is to evaluate the usefulness and effectiveness of vitamin D and D3 as supports for photodynamic therapy. For this purpose, the Pubmed and Scopus literature databases were searched. The search keyword was: “vitamin D in photodynamic therapy”. In the analyzed articles (1979–2022), the authors found experimental evidence of a positive effect of vitamin D and D3 when used in conjunction with photodynamic therapy. An average of 6–30% (in one case, up to 10 times) increased response to photodynamic therapy was reported in combination with vitamin D and D3 as compared to photodynamic therapy alone. Implementing vitamin D and D3 as a supplement to photodynamic therapy is promising and may lead to further clinical trials and new clinical methodologies.

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.

OBJECTIVES

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.

Vitamin D Enhances ALA-Induced Protoporphyrin IX Production and Photodynamic Cell Death in 3-D Organotypic Cultures of Keratinocytes

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) is based upon the intracellular synthesis of protoporphyrin IX (PpIX), which absorbs light and targets metabolically active cells. We tested the hypothesis that levels of PpIX within keratinocytes might be increased by vitamin D (Vit D), a differentiation-promoting hormone. Vit D promoted terminal differentiation in monolayer cultures of rat epidermal keratinocytes (REKs), but high PpIX signals were found only in stratifying islands. To simulate a normal epidermis, REKs were grown in organotypic cultures. The presence of Vit D (10(-10) M for 4 days) led to heightened expression of terminal differentiation markers (stratum corneum, K10, and loricrin). PpIX levels, at 4 hours after addition of ALA (1 mM), were significantly increased in the Vit D-preconditioned cultures by confocal fluorescence microscopy and semiquantitative image analysis. Maximal PpIX induction was seen at (Vit D) 10(-12)-10(-10) M. Phototoxic cell killing after exposure to 635 nm light was significantly higher in Vit D-preconditioned cultures. No differences in apoptotic markers between Vit D and control cultures were seen, suggesting that Vit D augments photodynamic cell death via alternative pathways (e.g., necrosis). In summary, Vit D may be useful as a biological enhancer of ALA-based PDT.