Splenic, thymic, bony and lymph node metastases from orthotopic human lung carcinomas in immunocompromised mice.

In orthotopic animal models of human lung cancer, bone and lymph node metastases have been observed with high frequency after periods of a few weeks, but metastases to other organs are rare. This study evaluated development of distant metastases over a six-month period in a model of orthotopic lung carcinoma in immunocompromised mice. Human A549 lung adenocarcinoma cells were stably transfected to express high levels of green fluorescent protein. Suspensions of 1 x 10(6) cells were instilled into the lungs of athymic and SCID mice to produce orthotopic human lung carcinomas. All animals had primary tumors at termination of the experiment six months later. Splenic metastases and lymph node metastases were present in 70% of the animals and two of the three SCID mice had thymic metastases. Three animals had bony metastases. Thus, a high percentage of immunocompromised mice with orthotopic lung carcinomas ultimately develop metastases.