Bombesin (BBS) stimulates cellular proliferation of both normal and tr
ansformed cells. The mouse colon cancer cells (MC-26) possess specific
binding sites for BBS. The purpose of this study, therefore, was to e
xamine the effect of chronic administration of BBS on in vivo growth o
f MC-26 tumours in Balb/c mice and on survival of tumour-bearing mice.
Three groups of mice (n=10 each) inoculated with MC-26 cells received
either saline containing 0.1% bovine serum albumin (BSA), or BBS (5 m
ug kg-1 or 20 mug kg-1) dissolved with 0.1% BSA saline by intraperiton
eal route three times a day for 15 days. BBS increased weight, DNA and
RNA contents of MC-26 tumours. To examine the effect of BBS on surviv
al rates of mice with MC-26 tumours, three groups of mice (n=20 each)
were treated for 31 days, as above. One group of mice inoculated with
MC-26 cells received 0.1% BSA saline; the other group of MC-26-inocula
ted mice and the control group without tumour received BBS (5 mug kg-1
) dissolved with 0.1% BSA saline. BBS significantly decreased the surv
ival rate of mice bearing MC-26 tumours (median survival; saline group
: 42.5 days, BBS group: 32.0 days, P=0.037). None of the mice in the c
ontrol group died during the experiment. BBS may stimulate in vivo gro
wth of MC-26 cells through specific receptors.