Selenium Enhances the Efficacy of Radachlorin Mediated- Photodynamic Therapy in TC-1 Tumor Development

576 ONCOLOGY REPORTS 28: 576-584, 2012 Selenium enhances the efficacy of Radachlorin mediated- photodynamic therapy in TC-1 tumor development YONG-WAN KIM1, SU MI BAE1, HAI-BO LIU1, IN-WOOK KIM1, HEUNG-JAE CHUN2 and WOONG SHICK AHN3 1Catholic Research Institutes of Medical Science, 2Institute of Cell and Tissue Engineering and 3Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea Received January 17, 2012; Accepted March 9, 2012 DOI: 10.3892/or.2012.1820 Abstract. Selenium, an essential trace element possessing anti- tive photodynamic destruction of tumor cells. The evident carcinogenic properties, can induce apoptosis in cancer cells. advantage of PDT over other conventional cancer treatments Our goal was to investigate the enhanced antitumor effects of such as chemotherapy and radiotherapy is its minimal invasive- photodynamic therapy (PDT) plus selenium in TC-1 tumor cells ness, selective targeting, and reduced toxicity, which allows and implanted mice. Cell viability was evaluated at various time for repeated treatment (1). Currently, PDT is being success- intervals after PDT treatment and/or selenium by methyl thia- fully used for the treatment of early lung cancers (2,3) and in zolyl tetrazolium (MTT) assay. When only PDT treatment was dermatology for the treatment of non-melanoma skin cancers administered to TC-1 tumor cells, TC-1 cell growth recovered and precancerous diseases (4). PDT has also been successfully over time. On the other hand, co-treatment of PDT and selenium employed to treat early carcinomas of the oral cavity and larynx extended the inhibition time of tumor cell growth. Co-treatment to preserve normal tissue and improve cure rates (5). Though of PDT and selenium showed serious morphological changes in therapeutic responses are encouraging, recurrences have been TC-1 cells and induced a more apoptotic population by FACS noticed due to incomplete PDT, which consequently triggers analysis. By signal transduction pathway SuperArray analysis, tumor angiogenesis. Non-homogeneous light distribution, genes closely involved in the NFκB, p53 and phopholipase C incomplete photosensitizer dosage, and tissue/tumor dynamics pathways, such as VCAM1, MDM2 and FOS, were significantly are some of the factors that impose constraints on the efficacy downregulated at least 10-fold in TC-1 cells following PDT of PDT. Moreover, as PDT-induced oxidative stress can cause and selenium cotreatment. In an in vivo study, tumor-bearing hypoxic conditions in the surviving tumor cells, it can elicit the mice were intravenously injected with Radachlorin 3 h before expression of angiogenic growth factors and cytokines as an irradiation with 300 J/cm2 of light. Selenium was administered adaptive response (6,7). Hypoxia is also known to reduce tumor daily for 20 days. Combination therapy against the mouse sensitivity to radiation therapy and chemotherapy that is associ- tumors generated by TC-1 cells was more effective than PDT ated with decreased local tumor control (8,9). Thus, further study or selenium alone. These data suggest that selenium plus PDT of controlling unwanted growth-stimulatory pathways after PDT can induce a significant tumor suppression response compared is desirable to minimize the risk of harmful adverse effects. with PDT alone. Additionally, it can be an effective anticancer Selenium is an important antioxidant nutrient that supports therapy strategy. the production of enzymes that protect cells against oxidant stress (10). Since oxidants can damage DNA, leading to poten- Introduction tially carcinogenic mutations, good selenium status has clearly anti-mutagenic potential. Epidemiological studies have pointed Photodynamic therapy (PDT) is an oxygen-mediated, minimally to the decrease of risks for certain cancers in people who have invasive therapeutic modality. It involves the administration of a relatively high selenium intakes or who live in regions of the tumor-localizing photosensitizer that is subsequently activated world where soil selenium levels are relatively high. The anti- with light of a specific wavelength, thus causing highly selec- carcinogenic effects of selenium against leukemia and cancers of the colon, rectum, pancreas, breasts, ovaries, prostate, bladder, lung, and skin have been reported (11). Anti-carcinogenic mechanisms in various cancers are related to reactive oxygen Correspondence to: Dr Woong Shick Ahn, Department of Obstetrics species (ROS) produced by redox cycling, modification of and Gynecology, College of Medicine, The Catholic University of protein-thiols, and methionine mimicry. Principal selenium Korea, 505 Banpodong, Seocho-ku, Seoul 137-040, Republic of Korea metabolites, such as hydrogen selenide, methylselenol, and E-mail: [email protected] selenomethionine execute anti-carcinogenic effects (12). Selenium compounds also can cause acute toxicity due to DNA Key words: photodynamic therapy, selenium, combination therapy, strand breaks by generating superoxide at high concentrations anti-cancer therapy of mainly inorganic forms. But many studies using different ΚΙΜ et al: COMBINATION THERAPY OF PDT AND SELENIUM 577 forms and doses of selenium have been reported; selenium automated spectrophotometer microtiter plate reader (Spectra doses involved in chemoprevention and tumor growth inhibition Max 340, Molecular Devices, CA, USA). remain to be elucidated (13). To induce effective anti-tumor response with low adverse Flow cytometry analysis. For cell cycle analysis, propidium effects, we attempted to co-treat with PDT and selenium. iodide (PI) staining was performed. Cells were collected, washed Combination therapy using low concentrations of photosen- twice with PBS, and then re-suspended in PI buffer (0.1% sodium sitizer and selenium may effectively reduce angiogenesis and citrate, Triton X-100, and 5 µg/ml propidium iodide). RNase A recurrence of cancer cells by PDT and selenium toxicity at a (250 µg/ml) was added to each cell sample, and the cells were high concentration. Additionally, apoptosis of cancer cells stained for 10 min in the dark. Flow cytometry was performed and continuous inhibition of cancer cell development may be on a FACScan automated system (Becton-Dickinson, Sunnyvale, induced more effectively. CA, USA), and data were analyzed using the CellQuest software package and ModFit LT 2.0 program. Materials and methods To determine apoptosis of TC-1 cells following treatments of PDT and/or selenium, TC-1 cells were collected at 48 h Ethics statement. All procedure of animal research were after all treatments and washed twice with PBS. The cells were provided in accordance with the Laboratory Animals Welfare stained with PI and annexin V-FITC. Annexin V-FITC staining Act, the Guide for the Care and Use of Laboratory Animals and was performed with an apoptosis detection kit (Invitrogen, the Guidelines and Policies for Rodent experiment provided by Camarillo, CA, USA) as described by the manufacturer's the IACUC (Institutional Animal Care and Use Committee) in instructions. The cells were analyzed using a FACScan flow School of Medicine, The Catholic University of Korea (permit cytometer (Becton-Dickinson) at 488 nm laser light excita- no: CUMC-2008-0062-02). tion. The cell populations were observed in a dot plot graphic. The population of apoptotic cells was represented as annexin Cell culture and tumor model. A murine cell line, TC-1 (ATCC V-positive and PI-negative cells, the population of necrotic cells CRL-2785) was cotransformed by HPV-16 E6/E7 oncoproteins was represented as annexin V-negative and PI-positive cells, and and c-Has-Ras and was cultured in RPMI-1640 medium (Gibco the population of late apoptotic/necrotic cells were represented BRL, Rocksville, MD) supplemented with 5% fetal bovine as annexin V-positive and PI-positive cells. serum (FBS; Gibco BRL). Streptomycin/penicillin (Gibco BRL), L-glutamine (Gibco BRL), 2.2 mg/ml sodium bicarbonate Real-time quantitative PCR (QPCR)/microarray analysis. Total (Sigma, St. Louis, MO), and 0.4 mg/ml G418 disulfate (Duchefa, RNA was isolated using TRIzol (Invitrogen Life Technologies, The Netherlands) were added to the culture medium, and the Carlsbad, CA) from TC-1 cells previously treated with PDT, cells were maintained at 37˚C in a 5% CO2 humid environment. selenium, or PDT plus selenium for 48 h. Reverse transcription Specific pathogen-free female C57BL/6 mice 6-7 weeks of was performed using the RT2-First Strand Kit (SuperArray age were purchased from Orient Bio (Seongnam, Korea) and Bioscience Corp., Frederick, MD) according to the manu- maintained in the specific pathogen-free animal facility. Five to facturer's protocol. Gene profiling was performed using the six mice were housed per cage under standard conditions. Mice RT2-profiler PCR array Mouse Signal Transduction Pathway were fed standard laboratory chow and water. The depilated Finder PCR Array (89 genes including 5 housekeeping genes). lower dorsa of the mice were injected subcutaneously with 5x105 The reactions were carried out in a Stratagene Mx 3000P real- TC-1 cells to generate the tumor model. Tumor growth was time PCR system (Stratagene, La Jolla, CA). The values were documented regularly by Vanier calipers in three orthogonal obtained for the threshold cycle (Ct) for each gene and normal- dimensions. Tumors were used for experimentation 10-12 days ized using the average of the 5 housekeeping genes on the same after inoculation when reaching surface diameters of 10-12

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