Putative role of heparan sulfate proteoglycan expression and shedding on the proliferation and survival of cells after photodynamic therapy

INTRODUCTION

Photodynamic therapy is based on the selective retention of a photosensitizer by highly proliferating cells and its activation with light at the appropriate wavelength. This combination generates reactive oxygen species that ultimately kill the cells. Some cells, however, may survive photodynamic therapy and the interaction of these cells with the extracellular matrix has profound effect in tumor biology. The knowledge of photodynamic therapy action on the extracellular matrix has not been fully explored. It has been focused mainly on integrins, matrix metalloproteinases and on growth factors and immunological mediators. Other important molecules involved in the regulation of many cell processes are the glycosaminoglycans, polymers of disaccharide units, present on the cell surface and in the extracellular matrix. In most cases, the glycosaminoglycans occur as proteoglycans.

AIMS

The purpose of the present investigation is to evaluate heparan sulfate proteoglycan expression and shedding, and its relation to the survival of the remaining cells, after a liposomal-AlClPc based photodynamic treatment.

MATERIALS

A wild-type endothelial cell derived from rabbit aorta and its counterpart transfected with EJ-ras oncogene were used.

RESULTS

Both cell lines presented augmented heparan sulfate proteoglycan syndecan-4 mRNA expression, augmented synthesis of heparan sulfate chains and increased shedding. Also, the formation of stress fibers on the border of the cells and the arrest in G(1) phase of the cell cycle was observed.

CONCLUSIONS

These results show that surviving cells after photodynamic therapy exhibit changes in their morphology and cell processes that differ from that of non-treated cells, and these changes are probably hindering the cells from resuming normal proliferation.

Ultrastructural effects of two phthalocyanines in CHO-K1 and HeLa cells after laser irradiation

The effects of Photodynamic Therapy using 2nd generation photosensitizers have been widely investigated aiming clinical application treatment of solid neoplasms. In this work, ultrastructure changes caused by the action of two 2nd generation photosensitizers and laser irradiation on CHO-K1 and HeLa (neoplastic) cells were analyzed by transmission electron microscopy. Aluminum phthalocyanine chloride, aluminum phthalocyanine tetrasulfonate chloride and radiation from a semiconductor laser at a fluency of 0.5 J/cm2 (Power=26 mW; lambda=.670 nm) were used. The results showed induction of apoptosis. Such alterations where observed in HeLa but not in CHO-K1 cells after Aluminum phthalocyanine tetrasulfonate chloride (AlPcS4, photodynamic treatment. The Aluminum phthalocyanine chloride (AlPc) photodynamic treatment induced necrosis on the neoplastic cell line, and cytoplasm and nuclear alterations on the normal cell line.