Dae-Seog Lim

Photoinactivation of vesicular stomatitis virus by a photodynamic agent, chlorophyll derivatives from silkworm excreta.

The efficacy of chlorophyll derivatives from silkworm excreta (CpD) in photodynamic antimicrobial chemotherapy (PACT) was studied. An enveloped animal virus, vesicular stomatitis virus (VSV), was used as a target organism. For CpD mediated PACT, the viruses in suspensions were treated with various doses of CpD (15-60 microg/ml) and visible red light was fixed at 120 mJ/cm(2). The antiviral effect of the CpD-PACT was measured 1 h after light irradiation by the extent of suppression of plaque forming units (pfu). In cultures inoculated with PACT-treated VSV, suppression of pfu was prominent and the results were demonstrated in a dose-dependent manner. In assays of RT-PCR, a single dose of 30 microg/ml CpD and light caused complete inhibition of viral RNA synthesis in the host cells, which agreed with the complete loss of plaque forming activity observed in pfu assays. An in vitro transcription assay for viral RNA using [3H]UTP and gel electrophoresis for the level of M protein was conducted. A gradual decrease in viral RNA transcription and an immediate decrease in M protein levels were observed in cells inoculated with the CpD-PACT-treated virus. These results demonstrated that CpD is a potential photodynamic antiviral agent, which causes inactivation of the matrix protein as well as transcription mechanisms involved in VSV replication.

DH-I-180-3-Mediated Photodynamic Therapy: Biodistribution and Tumor Vascular Damage

Abstract An important goal of photodynamic therapy (PDT) for treatment of various cancers is to shorten PDT-performing time and simultaneously enhance PDT efficacy. Here, we investigated the nontumor tissue distribution of and the tumor vascular damage caused by a new photosensitizer, DH-I-180-3, in mice with implanted EMT6 mammary tumor cells. In addition, we performed cell-based assays to evaluate the basic antitumor effect of DH-I-180-3/PDT in EMT6 cells. After administration of PDT, the type of cell death was characterized to be apoptosis, and a change in the mitochondrial membrane potential was also observed within minutes. On the other hand, tumor growth was remarkably retarded in vivo in mice that received DH-I-180-3/PDT, compared with mice in the control group, which were exposed to light irradiation alone. Finally, tumors in some mice nearly healed. The antitumor drug reached a maximum concentration approximately 3 h after administration. However, PDT was most effective when there was substantial accumulation of DH-I-180-3 in the tumor vasculature and in healthy tissue. The histological demonstration provided further evidence of tumor vascular damage. On the basis of these findings, we suggest that PDT with the photosensitizer DH-I-180-3 induces vascular damage with blood vessel shutdown, in addition to direct killing of tumor cells, in mice.

Photodynamic anti-tumor activity of a new chlorin-based photosensitizer against Lewis Lung Carcinoma cells in vitro and in vivo

A biological significance of photodynamic therapy (PDT) with a new porphyrin derivative, DH-I-180-3 (Max. Abs. 666 nm), was examined. Experimental PDT with DH-I-180-3 against Lewis Lung Carcinoma 1 (LLC1) cells was designed in vitro and in vivo. For the comparison, PDT with an established photosensitizer, Photofrin®, was done. When the cells were treated with DH-I-180-3 (1.0 μg/ml) in vitro, the cells became fatally susceptible to the light (1.2 J/cm2) as early as in 1 h. All of these cells were irreversibly damaged in 24 h after light irradiation and categorized as necrosis. These were not seen in cells treated with Photofrin® for more than 4 h and remained unharmed by the light until the end of experiments. Mice (C57BL/6J) bearing LLC1 tumor were treated (intravenously) with DH-I-180-3 (400 to 800 μg/kg) or with Photofrin® (2 mg/kg) for 4 h. Following the light irradiation (1.2 J/cm2), retarded tumor growth was significant in mice treated with DH-I-180-3 compared with those treated with Photofrin®/PDT. ...

Separation and Characterization of Chlorophyll Degradation Products in Silkworm Using HPLC‐UV‐APCI‐MS

Abstract By use of HPLC‐UV‐APCI‐MS, the chemical nature of chlorophyll degradation products (CpD) in the excreta of the silkworm (Bombyx mori) was clarified in relation to its photosensitizing efficacy in photodynamic therapy (PDT) of tumors in vitro. Besides CpD from silkworm excreta aged in nature for more than a year, mulberry leaves, substances in the digestive system of silkworms fed on the mulberry leaves, and fresh excreta less than 24 hrs old were analyzed and compared. The CpDs isolated were separated and characterized, and their photosensitizing efficacy in experimental PDT was evaluated. Among the agents characterized by HPLC‐UV‐APCI‐MS, pheophorbide‐a and pyropheophorbide‐a exerted the most potent photosensitizing effect in vitro. Although these pigments were detected in silkworm excreta, the amounts extracted were significantly higher in materials aged for more than one year. Yields from fresh excreta or digestive tract contents were lower than from stored excreta. None of those CpDs were detected in mulberry leaves. Natural environments presumably provide favorable conditions for the degradation of chlorophyll to pheophorbide‐a and/or pyropheophobide‐a.

Tetraarsenic Oxide-mediated Apoptosis in a Cervical Cancer Cell Line, SiHa

PURPOSE Diarsenic oxide, As(2)O(3), has been reported to be effective in treating acute leukemia, and induce apoptosis in many tumor cells. In this study, the ability of a novel arsenical compound, As(4)O(6) (tetraarsenic oxide), along with As(2)O(3), for its ability to induce cell growth inhibition, as well as apoptosis, in human cervical cancer cells, SiHa cells, were evaluated in vitro. MATERIALS AND METHODS To examine the levels of apoptosis, SiHa cells were given two sensitive doses, 0.5 and 1 microM, of arsenical compounds, and a DNA fragmentation assay and FACS analysis were then conducted. In addition, a Western blotting assay was performed to identify target molecules for apoptosis. RESULTS Both As(2)O(3) and As(4)O(6) induced dosedependent inhibition of SiHa cell proliferation. In particular, As(4)O(6) was more effective at suppressing SiHa cell growth than As(2)O(3). In parallel with the inhibition of cell proliferation, As(4)O(6) caused a significantly greater increase in the sub-G1 cell population than As(2)O(3), as determined by propidium iodide DNA staining. This was confirmed by a DNA fragmentation assay and annexin V staining. The Western blotting analysis also showed that the expression of proliferating cell nuclear antigen (PCNA) was suppressed to a significantly greater extent by As(4)O(6) than As(2)O(3) at a dose of 0.5 microM. However, the apoptosis-related protein, Bax, was expressed to a significantly greater extent due to As(4)O(6) than As(2)O(3). CONCLUSION Taken together, these findings suggest that a novel arsenic compound, As(4)O(6), possesses more potent anti-proliferative effects on human cervical cancer cells, with the induction of apoptosis also, at least via the activation of Bax protein in vitro.

Photodynamic effects of Radachlorin® on cervical cancer model

Photodynamic therapy (PDT) has been reported to be effective for treating various tumors and induce apoptosis in many tumor cells. In this study, we examined a biological significance of PDT with a chlorin-based photosensitizer, Radachlorin®, in a cervical cancer model, TC-1 cells. When TC-1 cells were exposed to varied doses of Radachlorin® with light irradiation (6.25 J/cm2), PDT induced a dose-dependent growth inhibition of TC-1 cells. All of these cells were significantly damaged after light irradiation and categorized to be early and late apoptosis, as determined by annexin V staining. Radachlorin® localized primarily into the Golgi apparatus of cells in 12 h of the treatment, and weak fluorescence intensity was also detected in mitochondria. On the other hand, in the in vivo experiments, following light irradiation (100 J/cm2), retarded tumor growth was significant in mice treated with Radachlorin®, as compared to the control group. Taken together, we propose that PDT after the application of Radachlorin® may induce the Golgi apparatus-mediated apoptosis of cervical cancer cells in vitro, and also be effective in the mice system.

Retraction: tetraarsenic oxide-mediated apoptosis in a cervical cancer cell line, SiHa.

Published: Cancer Res Treat. 2005;37(5):307-312 All authors unanimously wish to retract this paper as soon as possible. We deeply apologize to the readers for any inconvenience caused by this retraction.