Ablation of host submaxillary glands modifies Ehrlich tumor growth and tumo
r-infiltrating leukocytes, possibly by modifications in the serum level of
growth factors produced by this gland. To extend this research, 7-month-old
male EPM-1 mice (N = 30) were divided into two groups: 1) inoculated with
tumor cells previously incubated with submaxillary salivary gland extract (
SGE) in PBS for 30 min at 37%; 2) inoculated with tumor cells previously in
cubated with PBS, under the same conditions. Animals were inoculated into t
he footpad with 40 mu l of a suspension containing 4.5 x 10(7) tumor cells/
ml, and footpad thickness was measured daily for 10 days. Sections and smea
rs of tumor cells were prepared from the tumor mass to determine mitosis fr
equency, percent of tumor cells immunopositive to nerve (NGF) and epidermal
(EGF) growth factors and percent of tumor-infiltrating leukocytes. The inc
ubation of tumor cells with SGE produced a tumor reduction of about 30% in
size (P<0.01). This effect was not related to loss of cell viability during
incubation, but a 33% increase (P<0.05) in the percentage of dead or dying
tumor cells and a 15% increase in the percent of NGF/EGF-positive tumor ce
lls (P<0.01) were observed in vivo at the end of experiment. Tumor-infiltra
ting lymphocytes and mitosis frequency did not differ between groups. These
data suggest a direct effect of factors present in SGE on tumor cells, whi
ch induce degeneration of tumor cells.