Cells resistant to ALA-photodynamic therapy: Decreased metastatic phenotype and cytoskeleton changes

BATLLE A; DI VENOSA G; SANZ-RODRIGUEZ F; VANZULLI S; PEROTTI C; SIMIAN M; PONTIGGIA O; HASSAN T; STOCKERT J C; JUARRANZ A; CASAS A

Dubrovnik, Croacia

Congreso; First Meeting of the European Platform for Photodynamic Medicine - EPPM-1; 2008

European Platform for Photodynamic Medicine

Photodynamic therapy (PDT) is a novel cancer treatment modality utilizing a photosensitizer, visible light and oxygen. PDT often leaves a significant number of surviving cells. Previously, we isolated and studied two PDT resistant clones from the murine mammary adenocarcinoma LM3 line. The isolated Clone 4 and Clone 8 exhibited a more fibroblastic, dendritic pattern and were larger than the parentals. Here, we studied the metastasic potential of the two clones compared with LM3. We studied in vitro the adhesive and invasive characteristics, together with the proteolytic enzymes profile and changes in the expression of cytoskeletal and adhesion proteins. In vivo, we assayed the ability of resistant clones to induce spontaneous metastasis. We found that 100% of LM3 were able to invade Matrigel, whereas Clones 4 and 8 only invaded. 100% of LM3 cells migrated towards a chemotactic stimuli whereas 38±8% and 73±10% of Clones 4 and 8 migrated. In vivo, 100% of LM3 injected mice developed spontaneous lung metastasis, whereas none of Clone 8 did, and only one of the injected mice with Clone 4. No differences were found in the proteolytic enzyme profiles among the cells. Anchorage-dependent adhesion was also impaired in vivo in the resistant clones, evidenced by lower tumor take, latency time and growth rates, although both clones showed higher binding to collagen I without overexpression of 1 integrin. Changes of the metastasis phenotypes are due to differences in expression of F-actin in both clones, and E-cadherin, -catenin and vinculin specially in Clone 8.