Heat sensitivity and membrane properties of metastasizing and non-metastasizing rat mammary tumors.

Paired lines of metastasizing and non-metastasizing transplantable rat mammary tumors were studied for their sensitivity to hyperthermia. The metastasizing TMT-081 and SMT-2A tumors were markedly more sensitive to heat injury as measured by tumor growth delay than were their non-metastatic counterparts MT-100 and MT-W9B. The metastasizing MT-081 tumor was also significantly more sensitive than the SMT-2A tumor. The differences in heat sensitivity were not the result of differences in intra-tumor temperatures attained during water bath heating. A more likely explanation for the variable response obtained with these tumors after heat treatment may be the inherent differences in stability and composition of their cellular membranes, particularly the plasma membrane.