Differential response to heat of metastatic and non-metastatic rat mammary tumors.

Metastasizing and non-metastasizing transplantable mammary tumors were implanted into female W/Fu rats. A pair of tumors were employed, the SMT-2A and MT-W9B. When these tumors were exposed to water bath heating at 43.5 degrees C for 60 minutes, a significantly longer tumor-free growth delay was obtained in the metastasizing tumor compared to its non-metastasizing counterpart. The protein to phospholipid ratio and the content of arachidonic acid was lower in the metastasizing tumor than in the non-metastasizing one. By way of apparent compensation, the metastasizing tumor contained more linoleic and stearic acid. These observations suggest a relation between metastasizing capacity, thermal sensitivity, and membrane composition.