Establishment and Characterization of Canine Malignant Mesothelioma Cells.

BACKGROUND

We established persistently passable canine malignant mesothelioma (cMM) cell lines from tumor samples obtained from affected dogs, analyzed their characteristics, and investigated their sensitivity to anticancer drugs and photodynamic therapy (PDT) using 5-aminolevulinic acid hydrochloride (5-ALA).

METHODS

Histopathological analyses were performed on SDK cells cultured under two-dimensional (2D) and three-dimensional (3D) conditions, as well as on tumor tissues derived from SDK cells. Cell proliferation in both culture systems and sensitivity to anticancer agents and PDT were assessed.

RESULTS

In 2D culture, SDK cells appeared round to polygonal, with marked variability in size and the presence of pyknotic nuclei. In 3D culture, both large and small cells formed loose clusters with scattered cellular processes. Following subcutaneous transplantation into mice, tumor masses exhibited nodular lesions composed of tumor cells and fibroblasts. Cytokeratin expression was prominent in 3D-cultured cells and tumor tissues but weak in 2D-cultured cells. Vimentin and calretinin were expressed in all cells. SDK cells showed minimal sensitivity to carboplatin but were sensitive to doxorubicin. Notably, SDK cells were also sensitive to 5-ALA-mediated PDT.

CONCLUSION

SDK cells may serve as a novel cell line for elucidating the pathogenesis of cMM and for developing new therapeutic strategies.