Atorvastatin preferentially inhibits the growth of high ZEB-expressing canine cancer cells

Comparison of the anticancer effects of various statins on canine oral melanoma cells

Canine oral melanoma is a highly malignant cancer with a poor prognosis. Statins, commonly used drugs for treating dyslipidemia, exhibit pleiotropic anticancer effects and marked anti-proliferative effects against melanoma cells. The anticancer effects among statins vary; in human cancers, lipophilic statins have shown stronger anticancer effects compared with hydrophilic statins. However, data on the differences in the effects of various statins on canine cancer cells are lacking, hence the optimal statins for treating canine melanoma remain unknown. Therefore, this study aimed to clarify the most effective statin by comparing the anticancer effects of hydrophilic rosuvastatin and lipophilic atorvastatin, simvastatin, fluvastatin and pitavastatin on three canine oral melanoma cell lines. Time-dependent measurement of cell confluence showed that lipophilic statins had a stronger anti-proliferative effect on all cell lines than hydrophilic rosuvastatin. Quantification of lactate dehydrogenase release, an indicator of cytotoxicity, showed that lipophilic statins more effectively induced cell death than hydrophilic rosuvastatin. Lipophilic statins affected both inhibition of cell proliferation and induction of cell death. The anticancer effects of statins on canine oral melanoma cells differed in the following ascending order of IC50 values: pitavastatin < fluvastatin = simvastatin < atorvastatin < rosuvastatin. The required concentration of pitavastatin was approximately 1/20th that of rosuvastatin. Among the statins used in this study, pitavastatin had the highest anticancer effect. Our results suggest lipophilic pitavastatin as the optimal statin for treating canine oral melanoma.

Phenotypic and molecular characterization of novel pulmonary adenocarcinoma cell lines established from a dog

Canine pulmonary adenocarcinoma (PAC) resembles human lung tumors in never-smokers, but it is rarer than human pulmonary adenocarcinoma. Therefore, research on canine PAC is challenging. In the present study, we successfully established various novel canine PAC cell lines from a single lesion in a dog, including two parent cell lines and fourteen cloned cell lines, and characterized their cellular properties in vitro. Several of these cell lines showed epithelial-mesenchymal transition (EMT)-like and/or cancer stem cell (CSCs)-like phenotypes. We additionally assessed the sensitivity of the cells to vinorelbine in vitro. Three clonal lines, two of which showed EMT- and CSC-like phenotypes, were resistant to vinorelbine. Furthermore, we evaluated the expression and activation status of EGFR, HER2, and Ras signaling factors. The findings indicated that the cell lines we established preserved the expression and activation of these factors to varying extents. These novel canine PAC cell lines can be utilized in future research for understanding the pathogenesis and development of treatments for canine PAC.