Photodynamic therapy (PDT) employing methyl δ-aminolevulinic acid (Me-ALA), as a precursor of the photosensitizer protoporphyrin IX (PpIX), is used for the treatment of non melanoma cutaneous cancer (NMCC). However, one of the problems of PDT is the apparition of resistant cell populations. The aim of this study was to isolate and characterize squamous carcinoma cells SCC-13 resistant to PDT with Me-ALA. The SCC-13 parental population was submitted to successive cycles of Me-ALA-PDT and 10 resistant populations were finally obtained. In parental and resistant cells there were analyzed the cell morphology (toluidine blue), the intracellular PpIX content (flow cytometry) and its localization (fluorescence microscopy), the capacity of closing wounds (scratch wound assay), the expression of cell-cell adhesion proteins (E-cadherin and β-catenin), cell-substrate adhesion proteins (β1-integrin, vinculin and phospho-FAK), cytoskeleton proteins (α-tubulin and F-actin) and the inhibitor of apoptosis protein survivin, in the activated form as phospho-survivin (indirect immunofluorescence and Western blot). The results obtained indicate that resistant cells showed a more fibroblastic morphology, few differences in intracellular content of the photosensitizer, higher capacity of closing wounds, higher number of stress fibers, more expression of cell-substrate adhesion proteins and higher expression of phospho-survivin than parental cells. These distinctive features of the resistant cells can provide decisive information to enhance the efficacy of Me-ALA applications in clinic dermatology.

Photodynamic therapy (PDT) is widely used to treat non-melanoma skin cancer. However, some patients affected with squamous cell carcinoma (SCC) do not respond adequately to PDT with methyl-δ-aminolevulinic acid (MAL-PDT) and the tumors acquire an infiltrative phenotype and became histologically more aggressive, less differentiated, and more fibroblastic. To search for potential factors implicated in SCC resistance to PDT, we have used the SCC-13 cell line (parental) and resistant SCC-13 cells obtained by repeated MAL-PDT treatments (5th and 10th PDT-resistant generations). Xenografts assays in immunodeficient mice showed that the tumors generated by resistant cells were bigger than those induced by parental cells. Comparative genomic hybridization array (aCGH) showed that the three cell types presented amplicons in 3p12.1 CADM2, 7p11.2 EFGR, and 11q13.3 CCND1 genes. The 5th and 10th PDT-resistant cells showed an amplicon in 5q11.2 MAP3K1, which was not present in parental cells. The changes detected by aCGH on CCND1, EFGR, and MAP3K1 were confirmed in extracts of SCC-13 cells by reverse-transcriptase PCR and by western blot, and by immunohistochemistry in human biopsies from persistent tumors after MAL-PDT. Our data suggest that genomic imbalances related to CCND1, EFGR, and particularly MAP3K1 seem to be involved in the development of the resistance of SCC to PDT.

Nanoberries could be effective to protect the skin from sun photodamage.

Triarylmethane and thiazine dyes have attracted attention as anticancer and antimicrobial agents, due to their structural features and selective localizations. Although these dyes have been initially explored in the context of photodynamic therapy, some of these such as New Fuchsin and Azure B have still not been extensively investigated. For this reason, we evaluated the chemical stability, aggregation effect, and lipophilicity, as well as the photodynamic activity against LM-2 murine mammary carcinoma cells of five new brominated dyes of triarylmethane and thiazine. These cationic compounds were obtained at high purities and unequivocally characterized by conventional techniques. The introduction of bromine atoms into the chromophoric system of New Fuchsin and Azure B dyes gave rise to a moderate bathochromic shift and increased the lipophilicity, thereby improving their photophysical and photochemical properties for biomedical applications. Moreover, the in vitro photodynamic activity demonstrated that, as the degree of bromination increased, the phototoxicity remained unchanged or decreased. The lower efficiency to inactivate cultured tumor cells may be attributed to the formation of the colorless carbinol pseudobase and aggregation effects for triarylmethane and thiazine dyes, respectively. A promising strategy to reverse the biological activity decrease observed might be the design of third-generation photosensitizers.

Abstract. in the present study, a comparative photodynamic therapy (pdt) study was performed using the phthalocyanine derivatives, Znpc(Och 3 ) 4 and Znpc(cF 3 ) 4 , in a mouse tumor model, under identical experimental procedures. We studied the ablation of tumors induced by pdt. the end-point was to compare the photodynamic efficacy of ZnPc(OCH 3 ) 4 and Znpc(cF 3 ) 4 . Znpc(Och 3 ) 4 and Znpc(cF 3 ) 4 were administered intraperitoneally at a dose of 0.2 mg/kg body weight. the injections of drugs were carried out in Balb/c mice bearing subcutaneously inoculated lm2 mouse mammary adenocarcinoma. histological examination and serum biochemical parameters were used to evaluate hepatic and renal toxicity and function. phototherapeutic studies were achieved employing a light intensity of 210 J/cm 2 . after pdt, tumoral regression analyses were carried out, and the degree of tumor cell death was measured utilizing the vital stain Evan's blue. in this pilot study, we revealed that the cytotoxic effect of Znpc(Och 3 ) 4 after pdt led to a higher success rate compared to Znpc(cF 3 ) 4 -pdt when both were intraperitoneally injectioned. Both phthalocynanine derivatives were able to induce ablation in the tumors. in summary, these results demonstrate the feasibility of Znpc(Och 3 ) 4 -or Znpc(cF 3 ) 4 -pdt and its potential as a treatment for small tumors. Introductionphotodynamic therapy (pdt) is a well-known procedure in the field of clinical medicine for the treatment of cancer, although there has also been research into its application for non-malignant disorders, such as psoriasis or actinic keratosis and for cases of choroidal neovascularization.the treatment is currently under active investigation for palliative or curative applications. pdt is an evolving cancer treatment that depends on three known and variable components: photosensitizer (pS), light and oxygen (1). pdt relies on selective accumulation of a pS in tumor tissue, which on illumination with light of appropriate wavelengths, generates reactive oxygen species, particularly singlet oxygen, and destroys tumor tissue (2). in recent years, treatment of cancer by pdt has gained considerable interest due to its intrinsic dual selectivity. the pS localizes in the malignant tissue, and the light is spatially focused on the lesion (3). phthalocyanines (pcs) are pSs of the dye family. pcs and their derivatives have been intensively investigated as the second generation pSs for pdt (4). most of the activity of clinical pSs in the dye family comes from phthalocyanines and their relatives, the naphthalocyanines. these structures are active in a range of 650-850 nm. most dyes are hydrophobic requiring delivery agents, such as a liposomal preparation, for clinical use. Linking dyes to a variety of metals improves efficacy. aluminum, zinc and silicon appear to offer the best pdt activity (5).the development of new compounds as potential pSs in PDT is of great scientific interest. The advantage of this therapy over available therapies is the high selectivity of tumor des...

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