Effect of a submaxillary gland extract on Ehrlich tumor growth in mice

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.