Oxidative alterations inducedin vitroby the photodynamic reaction in doxorubicin-sensitive (LoVo) and -resistant (LoVoDX) colon adenocarcinoma cells

Abstract

In photodynamic therapy (PDT) a tumor-selective photosensitizer is administered and then activated by exposure to a light source of appropriate wavelength. Multidrug resistance (MDR) is largely caused by the drug efflux from the tumor cell by means of P-glycoprotein, resulting in reduced efficacy of the anticancer therapy. This study deals with photodynamic therapy with Photofrin (Ph) on colon cancer cell lines (doxorubicin-sensitive and -resistant). The cells were treated with 15 and 30 microg/mL Ph and then irradiated by a light dose of 3 or 6 J/cm(2) (632.8 nm). After irradiation the cells were incubated for 0, 3 or 18 h. Crucial factors of oxidative stress (thiobarbituric acid reactive substances [TBARS], protein damage, thiazolyl blue tetrazolium bromide [MTT] assay), changes in cytosolic superoxide dismutase (SOD1) activity after photodynamic reaction (PDR), and the intracellular accumulation of photosensitizers in the cells were examined. Moreover, the expressions of glutathione S-transferase (GST)-pi, a marker protein for photochemical toxicity, and secretory phospholipase A(2), a prognostic and diagnostic marker for colon cancers, were determined. After PDR, increases in SOD1 activity and the level of TBARS were observed in both cell lines. The level of protein-associated -SH groups decreased after PDR. Both cell lines demonstrated stronger GST-pi and PLA(2) expression after PDR, especially after 18 h of incubation. The increasing level of reactive oxygen species following the oxidation of sulfhydryl cell groups and lipid peroxidation influence the activity of many transporters and enzymes. The changes in SOD1 activity show that photodynamic action generates oxidative stress in treated cells. Our study presents that PDR caused oxidative alterations in both examined colon adenocarcinoma cell lines. However, the MDR cells reacted more slowly and all oxidative changes occurred in the delay.

Electric Field-Assisted Delivery of Photofrin to Human Breast Carcinoma Cells

“…The concept of Photofrin-mediated PDT enhanced with EP has not been studied yet; however, there are many studies on Photofrin-mediated PDT (Hajri et al 2002; Luo et al 2010; Tong et al 2000; Chang et al 2008; Korbelik and Krosl 1996; Henderson et al 2000; Schweitzer 2001; Jiang et al 1998; Kulbacka et al 2010). Several studies on Photofrin transport and accumulation mechanism were also conducted.…”

Effects of electrophotodynamic therapy in vitro on human melanoma cells – melanotic (MeWo) and amelanotic (C32)

“…We tested the effects of EP-mediated transport enhancement of the photosensitizer on cellular phototoxicity. The electric field, when selected appropriately, significantly increases the molecular transport of a drug and its intracellular concentration, with no significant destruction of the cell [26]. The EPDT applied in the amelanotic melanoma cells in vitro led to a five-fold increase in the cytotoxic effect and a more than 3.5-fold increase in cytotoxicity for the melanotic melanoma cells.…”

“…Furthermore, a significantly shorter exposure time (1 h instead of 4 h) was sufficient for the effect. The reduced exposure time is a characteristic advantage of enhancing PDT with EP [26]. The previous in-vitro melanoma study showed that PDT-based Photofrin is effective even without EP, but a much longer duration of incubation of Photofrin should be applied [18,19,21,34].…”

“…The application of a high electric field to the plasma membrane generates transient hydrophilic electropores [26]. The EP supports nonselective transport of nonpermeant molecules into the cell, which can be used for gene transfection or drug delivery [27][28][29].…”

Physicochemical properties of potential porphyrin photosensitizers for photodynamic therapy

“…Determination of the effect of the environment on test compounds is essential in photodynamic therapy process. This allows to predict how the photosensitizer will behave in contact with other compounds in the cell [14,15].…”