DIFFERENTIAL EFFECT OF HOST MICROENVIRONMENT AND SYSTEMIC HUMORAL-FACTORS ON THE IMPLANTATION AND THE GROWTH-RATE OF METASTATIC TUMOR IN PARABIOTIC MICE CONSTRUCTED BETWEEN YOUNG AND OLD MICE
R. Hirayama et al., DIFFERENTIAL EFFECT OF HOST MICROENVIRONMENT AND SYSTEMIC HUMORAL-FACTORS ON THE IMPLANTATION AND THE GROWTH-RATE OF METASTATIC TUMOR IN PARABIOTIC MICE CONSTRUCTED BETWEEN YOUNG AND OLD MICE, Mechanism of ageing and development, 71(3), 1993, pp. 213-221
B16 melanoma cells were injected into the tail vein of young mice, old
mice and parabiotic mice constructed between young and old mice, and
the number and shape of pulmonary metastases were compared among three
experimental groups. In unpaired mice, the number of metastatic colon
ies in the lungs was 10-fold larger in young than in old mice. In para
biotic mice, the number in young mice was almost comparable with that
of unpaired young mice, but the number in old mice approached the leve
l of young mice. Metastatic colonies on the pulmonary surface of young
mice were mostly nodular in shape, while those of old mice were flat
in shape. The shape of colonies reflecting the tumor growth rate did n
ot change in parabiotic old mice in spite of an increase in number. In
young parabiotic mice, the large and intermediate colonies decreased
with a concomitant increase of small ones as compared with unpaired yo
ung mice. These results suggest that the implantation of metastatic co
lonies in the lung is mainly dependent on systemic humoral factors and
their growth is mainly dependent on the host local factors in the mic
roenvironment, and distinct age changes of both factors greatly influe
nce the metastatic mode of tumors, respectively.