Novel enhanced lung-colonizing variant of murine MBT-2 bladder cancer cells.

Objectives. To develop an enhanced lung-colonizing variant of murine bladder cancer that will allow the mechanism of metastasis to be studied more readily. Methods. We implanted murine bladder tumor cells (MBT-2) into the leg muscles of C3H mice. We developed variant cells from a lung metastasis nodule. We compared the MBT-2 cells and variant cells (MBT-2V) in vivo by evaluating lung nodule formation, survival, in vitro adhesion, and migration-invasion assays. Zymography and semiquantitative reverse transcriptase-polymerase chain reaction analyses were also performed to characterize the metastatic ability of both cells. Results. MBT-2 and MBT-2V cells were tumorigenic when injected intramuscularly into C3H mice, but MBT-2 cells had little potential to metastasize compared with MBT-2V cells. Metastases were observed in the lungs of mice injected in the tail vein with MBT-2 and MBT-2V cells. Mice receiving MBT-2V cells had significantly shorter survival (P <0.01) and more lung nodules (245 versus 106, P <0.0001) than those receiving MBT-2 cells. In vitro study revealed that MBT-2V cells exhibited more adhesion, greater migration, and more invasiveness than did MBT-2 cells. Pathologic examination revealed the tumors from MBT-2V cells to be more aggressive than those from MBT-2 cells. MBT-2V also showed significantly greater matrix metalloproteinase-9 expression. Conclusions. We generated an enhanced lung-colonizing variant of MBT-2 cells. Our MBT-2V cells showed more aggressive and invasive metastatic ability than that of the MBT-2 cells. Zymography and reverse transcriptase-polymerase chain reaction analyses indicated that matrix metalloproteinase-9 might be associated with the metastatic ability of MBT-2V cells.