A suppository kit for metronomic photodynamic therapy: The elimination of rectal cancer in situ

Phonozen-mediated photodynamic therapy comparing two wavelengths in a mouse model of peritoneal carcinomatosis

BACKGROUND

This study assessed the therapeutic efficacy of intraperitoneal photodynamic therapy (PDT) using photosensitizer activation at two different wavelengths, 405 and 664 nm, in a mouse model of peritoneal carcinomatosis.

METHODS

The dark and light cytotoxicity of chlorin e6-polyvinylpyrrolidone (Phonozen) were measured in vitro under 402 ± 14 and 670 ± 18 nm LED activation in bioluminescent human gastric cancer cells, MKN45-luc. Cell viability was measured at 6 h after irradiation using the PrestoBlue assay. Corresponding in vivo studies were performed in athymic nude mice by intraperitoneal injection of 1 × 106 MKN45-luc cells. PDT was performed 10 d after tumor induction and comprised intraperitoneal injection of Phonozen followed by light irradiation at 3 h, delivered by a diffusing-tip optical fiber placed in the peritoneal cavity and coupled to a 405 or 664 nm diode laser to deliver a total energy of 50 J (20 mice per cohort). Whole-body bioluminescence imaging was used to track the tumor burden after PDT out to 130 days, and 5 mice in each cohort were sacrificed at 4 h post treatment to measure the acute tumor necrosis.

RESULTS

Photosensitizer dose-dependent photocytotoxicity was higher in vitro at 405 than 664 nm. In vivo, PDT reduced the tumor growth rate at both wavelengths, with no statistically significant difference. There was substantial necrosis, and median survival was significantly prolonged at both wavelengths compared with controls (46 and 46 vs. 34 days).

CONCLUSIONS

Phonozen-mediated PDT results in significant cytotoxicity in vitro as well as tumor necrosis and prolonged survival in vivo following intraperitoneal light irradiation. Blue light was more photocytotoxic than red in vitro and had marginally higher efficacy in vivo.

Photodynamic therapy with light-emitting diode arrays producing different light fields induces apoptosis and necrosis in gastrointestinal cancer

Introduction

Light-emitting diodes (LEDs) have become a new light source for photodynamic therapy (PDT) because of their excellent optical properties, small size, and low cost. LED arrays have so far been designed to meet the need for accurate illumination of irregular lesions. However, LED arrays determine not only the shape of the illuminated spot but also the light field, which has a significant impact on the efficacy of PDT.

Methods

We designed three types of LED arrays producing different light fields, namely an intensive LED array for a uniform light field, a sparse LED array for a non-uniform light field, and a point LED array for a Gaussian-like light field, and investigated the effect and mechanism of these light fields on PDT for gastrointestinal cancer both in vitro and in vivo.

Results

We found that intensive LED-PDT induced earlier and more serious cell death, including apoptosis and necrosis, than sparse LED-PDT and point LED-PDT. Among the three LED arrays, the intensive LED array induced cells to produce more differential proteins (DEPs), mainly related to mitochondria, ribosomes, and nucleic acids. DEPs in cells subjected to sparse LED- and point LED-PDT were mainly involved in extracellular activities. For MGC-803 tumor-bearing mice, intensive LED-PDT and point LED-PDT had better tumor ablation effect than sparse LED-PDT. Notably, recurrence was observed on day 7 after sparse LED-PDT. VCAM-1 and ICAM-1 were highly expressed in sparse LEDs-PDT treated tumor tissues and were associated tumor angiogenesis, which in turn lead to poor tumor suppression.

Conclusions

Therefore, the type of LED array significantly affected the performance of PDT for gastrointestinal cancer. Uniform light field with low power densities work better than non-uniform and Gaussian-like light fields.

Deep proteome profiling of SW837 cells treated by photodynamic therapy (PDT) reveals the underlying mechanisms of metronomic and acute PDTs

AIM

Metronomic photodynamic therapy (mPDT) with a longer irradiation time and lower energy compared with acute (or classic) photodynamic therapy (aPDT) is a more effective treatment than aPDT for tumor cells, especially colorectal cancer. However, the underlying mechanisms of the superior effects of mPDT are unknown.

METHODS

we used SWATH-MS (sequential window acquisition of all theoretical mass spectra) to identify differentially expressed proteins (DEPs) specific to aPDT (conventional fluence rate, 20 mW/cm², 4 min 10 s), mPDT (metronomic fluence rate, 0.4 mW/cm², 3.5 h), and control groups of SW837 cells. The photosensitizer used in both PDT methods was aminolevulinic acid which were incubated with the cells before irradiation.

RESULTS

A total of 6805 proteins were identified in the three groups of SW837 cells. aPDT induced 333 DEPs and mPDT induced 1716 DEPs compared with the control. We identified 185 common DEPs in the two PDT groups, 148 different DEPs in the aPDT group, and 1531 different DEPs in the mPDT group. Most of the 185 common DEPs were involved in the extracellular component, participated in the processes of vesicle transport and secretion, binding, and hydrolase/catalytic activity. They were also involved in PI3K-Akt, cGMP-PKG, RAS, and aAMP signaling pathways. In addition, the 1531 different DEPs in the mPDT group participated in similar processes and molecular functions, but in a more complex manner than those in the aPDT group.

CONCLUSION

our proteome data suggest that mPDT has a complex tumor destruction mechanism with more involved proteins compared with aPDT, which may explain the better tumor killing effect of mPDT.

Metronomic photodynamic therapy with 5-aminolevulinic acid induces apoptosis and autophagy in human SW837 colorectal cancer cells

Metronomic photodynamic therapy (mPDT) has emerged as an attractive treatment for the selective destruction of tumor cells by induction of apoptosis. Here, we compared the effects of mPDT and acute photodynamic therapy (aPDT) on human SW837 colorectal cancer (CRC) cells. CRC cells were subjected to mPDT using various exposure durations, concentrations of 5-aminolevulinic acid (ALA), fluence rates and energy densities. The effects were compared with those induced by aPDT. We found that apoptosis and autophagy were earlier induced to a greater extent by mPDT than by the same dose applied as aPDT. The survival rates for mPDT vs. aPDT were 35.2%, 32.4%,27.6%,31.6% vs. 85.7%, 71.1%, 67.8%, 42.1% after 3, 6, 12, and 24 h PDT, respectively. For the same time points, the apoptotic rates for mPDT vs. aPDT were 43.2%, 47.3%, 54.7%, and 50.3% vs. 14.6%, 17.6%, 27.1%, and 53.2%, respectively. mPDT induced a peak rate of autophagy of 20.0% at 3 h, whereas aPDT induced two smaller peaks at 3 h (14.1%) and 12 h (15.8%). Advanced autophagosomes were more abundant in mPDT- than aPDT-treated cells and appeared earlier after mPDT (3 h) than after aPDT (3-12 h). Western Bloting results showed that the ratio of LC3B-II/β - actin at 3 h was higher (1.04 times) after mPDT than aPDT. Collectively, these datas indicated that ALA-mPDT was more effective than the same dose of ALA-aPDT at inducing SW837 CRC cell death via apoptosis and autophagy. Thus, mPDT may be a superior choice than aPDT for the treatment of human CRC.