Up-regulation of clusterin during phthalocyanine 4 photodynamic therapy-mediated apoptosis of tumor cells and ablation of mouse skin tumors

K. Kalka, N. Ahmad, T. Criswell, D. Boothman, H. Mukhtar

Research output: Contribution to journalArticle

53 Scopus citations


Photodynamic therapy (PDT) using the silicon phthalocyanine photosensitizer Pc 4 is an oxidative stress associated with the induction of apoptosis in many cancer cells in vitro and in vivo. The mechanisms of PDT-induced tumor cell killing leading to apoptosis are incompletely understood. Clusterin, a widely expressed glycoprotein, is induced in tissues regressing as a consequence of oxidative stress-mediated cell death. Treatment of apoptosis-sensitive human epidermoid carcinoma cells (A431) with PDT resulted in significant up-regulation of clusterin with a maximum at 12 h after treatment, whereas clusterin levels in Pc 4-PDT-treated, apoptosis-resistant, radiation-induced fibrosarcoma (RIF-1) cells remained unchanged. The i.v. administration of Pc 4 to mice bearing chemically or UVB radiation-induced skin papillomas, followed by light application, led to increased clusterin protein expression, peaking 24 h after the treatment, when tumor regression was apparently visible. These data, for the first time, demonstrate the involvement of clusterin in PDT-mediated cell death and during tumor regression. This may have relevance in improving the efficacy of PDT using pharmacological inducers of clusterin.

Original languageEnglish (US)
Pages (from-to)5984-5987
Number of pages4
JournalCancer Research
Issue number21
Publication statusPublished - Nov 1 2000


ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this