Effects of photodynamic therapy with hypericin in mice bearing highly invasive solid tumors

The tumoricidal properties of photodynamic therapy (PDT) with hypericin (HY ) were evaluated in a highly metastatic adenocarcinoma (DA3(Hi)) and anapla stic squamous cell carcinoma (SQ2) tumors in vivo. Photosensitization of th e tumor site with hypericin (HY-PDT) reduced primary tumor development and significantly prolonged the survival of tumor-bearing (TB) mice. Of these t wo tumors the squarrous cell carcinoma emerged as more sensitive to HY-PDT compared with DA3(Hi) adenocarcinoma both in vitro and in vivo. HY-PDT caus ed extensive tumor necrosis that was followed by local, intratumoral, and s ystemic inflammatory reactions. Analyses of cytokine mRNA profiles reveal i ncreases in mRNA levels of expression confined to inflammation-related cyto kines both within the tumor and also systemically (measured in spleens). Ho wever, there was no evidence for any HY-PDT-induced antitumoral immune reac tions. Our results suggest that PDT with hypericin can be considered as a s upplementary treatment in the management of some invasive and metastatic ca ncers such as squamous carcinoma and similar tumors.