A possible relationship between the anti-cancer potency of photodynamic therapy using the novel photosensitizer ATX-s10-Na(II) and expression of the vascular endothelial growth factor in vivo

Abstract

ATX-s10-Na(II) is a novel second-generation photo-sensitizer for photodynamic therapy (PDT). PDT using ATX-s10 and diode laser (670 nm) induces an apoptotic response, inflammatory reaction, immune reaction and damage to the microvasculature. In particular, the vascular shutdown effect plays an important role in the anti-tumor activity of ATX-s10-PDT. It has been reported that PDT induces hypoxia and expression of the vascular endothelial growth factor (VEGF) via the hypoxia-inducible factor 1 (HIF1)-α pathway. We hypothesized that the expression of VEGF may cause tumor recurrence after PDT and exert unfavorable effect against the anti-tumor activity of ATX-s10-PDT. In this study, we showed by DNA microarray analysis in vitro that VEGF mRNA expression was induced 3 h after laser irradiation in ATX-s10-PDT. We compared the antitumor activity of ATX-s10-PDT against lung cancer cell lines SBC-3 and SBC-3/VEGF, the latter overexpressing VEGF; there was no significant difference in the sensitivity to the PDT between the two cell lines as assessed by clonogenic assay. Furthermore, no statistically significant difference in the anti-tumor effect of PDT, as measured by tumor cures, was found between SBC-3 and SBC-3/VEGF tumors in female Balb/c-nu/nu nude mice in vivo. In conclusion, ATX-s10-PDT may prevent tumor recurrence despite induction of VEGF and promotion of tumor angiogenesis, which are known to enhance tumor proliferation and survival.

High expression of GADD-45α and VEGF induced tumor recurrence via upregulation of IL-2 after photodynamic therapy using NPe6

“…Aliquots of the cells were seeded into 25 cm 2 flasks in amounts sufficient to yield 50-150 colonies. After incubation for 10-14 days, the cells were stained with 0.1% crystal violet in 20% ethanol, and colonies containing at ≥50 cells were counted (13,23,24). The plating efficiency of the untreated cells was 30-40%.…”

“…Gene expressions in the lung cancer cells, namely, SBC-3 cells before and 3 h after PDT, were analyzed using a cDNA microarray (13). PDT was applied to the SBC-3 cells at the LD 90 (10.0 μg/ml NPe6, 10J/cm 2 laser irradiation) dose and the mRNAs were extracted and purified using the total RNA kit (Qiagen, Hilden, Gemany).…”

“…A total of 1x10 7 LLC and LLC-IL-2 cells in a volume of 0.1 ml were injected s.c. into the right hind flank of the experimental mice. The tumor volume was measured twice a week using a pair of Vernier calipers (11)(12)(13). Seven to ten days after the transplantation, tumors measuring over 100 mm 3 were used for the PDT and surgical experiments.…”

“…Tumor volumes were calculated using the following formula: Tumor volume = LD2/2 (L, long diameter; D, short diameter). Tumor volumes >400 mm 3 were recorded and judged as representing recurrences (11)(12)(13)25).…”

“…Recently, we demonstrated using VEGF-overexpressing cells (SBC-3/VEGF) that PDT with ATX-s10 (Na), a novel second-generation photosensitizer, prevent tumor recurrence despite induction of VEGF and promotion of tumor angiogenesis (13). However, the relationship between the anticancer potency of PDT and the expressions of cytokines, such as VEGF, is still controversial.…”