The relationship of blood vessel proximity and time after radiolabeled thymidine administration to tumor cell population kinetics in a transplanted mouse mammary tumor.

The relation between the time of administration of tritiated thymidine and the proximity of cells to blood vessels and their labeling index, grain density per labeled cells, mitotic index, and growth fraction have been determined autoradiographically in a transplanted mammary tumor of mice. The tumor was rich in blood vessels, and the cells were densely packed, showing a few glandular structures. Shortly after tritiated thymidine administration, cells closer to the blood vessels (0-70 mu) showed a higher percentage of labeled and mitotic cells, more grains per labeled cells, and a higher growth fraction than the cells located in the outer zone (70-140 mu). Eight days later the values of these parameters were similar in both areas. The cell cycle time, the duration of mitosis, the S phase, the G1 phase and the G2 phase were essentially the same in both zones. These results could be attributed either to reutilization of nucleic acid metabolites or release of the original precursor from cells. It is suggested that label redistribution, which may perturb the measurement of the apparent turnover of labeled proliferating cellular systems in the body should be considered in all cases of autoradiographic or labeled purine-pyrimidine turnover studies

Characterization of the metastatic properties of two methylcholantrene-induced fibrosarcoma in mice

MC1 and MC2 murine fibrosarcomas, following intramuscular innplantation in mice, release different numbers of tumor cells into the bloodstream and differ in their lung colonization potential following intravenous inoculation. Since these biological properties could be related to a different degree of maligancy, in vivo and in vitro experiments were performed vvith these two tunnors in an attempt to correlate their spontaneous metas-tatic potential with other parameters related to tunnor cell invasion and metastasis. Following intramuscular inplantation the MC2 fibrosarcoma was observed to have a slow but progressive ability to spontaneously metastasize while the MC1 lacked this capability. However, in an in vitro invasion assay the MC2 tunnor cell line vvas not able to degrade extracellular matrix (ECM), nor vas there any evidence for increased MC2 tumor degradative enzyme (8-N-acetylglucosaminidase). On the